Dinosaurs starting with letter A
As we add the information to the dinosaur name we will link to it (in red)
Although technically all true dinosaurs were terrestrial animals we are including the marine based creatures and the ancestors.
Adamantisaurus |
Adasaurus |
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Aeolosaurus |
Aerosteon |
Afrovenator |
| Alaskacephale | ||
| Aletopelta | ||
| Allosaurus | Altirhinus | |
Ammosaurus |
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Amphicoelias |
Anatosaurus |
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| Anurognathus | ||
Aralosaurus |
Archaeoceratops |
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| Arrhinoceratops | ||
| Aristonectes | Askeptosaurus | |
Atlascopcosaurus |
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| Australovenator | ||
| Avimimus |
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Try our A - Z of Dinosaur Pronunciations and Name Meanings 
Aardonyx - Lower Jurassic, South Africa
Aardonyx is a genus of prosauropod dinosaur. It is known from the type species Aardonyx celestae found from the Lower Jurassic Elliot Formation of South Africa. A. celestae was named after Celeste Yates, who prepared much of the first known fossil material of the species. It has arm features that are intermediate between prosauropods and sauropods.
Based on the structure of the hind limbs and pelvic girdle of Aardonyx, the dinosaur normally moved bipedally but could drop to quadrupedal movement similar to Iguanodon. It shares some attributes with giant quadrupedal sauropods like Apatosaurus. Australian paleontologist Adam Yates and his team's discovery of the genus was published online before print in Proceedings of the Royal Society B in November 2009, and is scheduled to appear in the March 2010 issue. British paleontologist Paul Barrett of the Natural History Museum, London, who was not involved in the research, commented that the discovery of Aardonyx "helps to fill a marked gap in our knowledge of sauropod evolution, showing how a primarily two-legged animal could start to acquire the specific features necessary for a life spent on all-fours".Aardonyx shows a transition toward the bulk-browsing form of feeding characteristic of sauropods. The jaws of Aardonyx are narrow and V-shaped with a pointed symphysis, a plesiomorphic characteristic shared with other basal sauropodomorphs. In sauropods, the jaws are broad and U-shaped to allow for a wider bite.
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Abelisaurus - Late Cretaceous, South America. 7-9m (25-30ft) long.
Abelisaurus is a genus of abelisaurid theropod dinosaur from the Late Cretaceous Period (Campanian) of what is now South America. It was a bipedal carnivore that probably reached 7 to 9 meters (25 to 30 feet) in length, although it is known from only one partial skull.
The generic name recognizes Roberto Abel as the discoverer of the specimen and former director of the provincial Museum of Cipolletti in Argentina, where the specimen is housed. There is one named species, A. comahuensis, which honors the Comahue region of Argentina, where the fossil was found. Both genus and species were named and described by Argentine paleontologists Jose Bonaparte and Fernando Novas in 1985, who placed it in the newly-created family Abelisauridae.
Many other abelisaurids have since been discovered, including extremely complete specimens of Aucasaurus, Carnotaurus and Majungasaurus. Some scientists place Abelisaurus as a basal abelisaurid, outside the subfamily Carnotaurinae.[2][3] Others are less certain of its position.[4][5] Abelisaurids share some skull features with the unrelated carcharodontosaurids and, since Abelisaurus is known only from a skull, future discoveries may show that this genus was in fact a carcharodontosaurid.[6] However, this is thought unlikely.[5]
The one known fossil skull of Abelisaurus is incomplete, especially on the right side. It is also missing most of the palate (roof of the mouth). Despite the missing pieces, it is over 85 centimeters (33 inches) long. Although there are no bony crests or horns, like those found in some other abelisaurids, such as Carnotaurus, rough ridges on the snout and above the eyes might have supported some kind of crest made out of keratin, which would not have become fossilized. There are also very large fenestrae (window-like openings) in the skull, which are found in many dinosaurs and reduce skull weight.[1]
From Wikipedia, the free encyclopedia
1. ^ a b Bonaparte, J.F. & Novas, F.E. 1985. [Abelisaurus comahuensis, n.g., n.sp., Carnosauria of the Late Cretaceous of Patagonia.] Ameghiniana. 21: 259-265. [In Spanish]
2. ^ Tykoski, R.S. & Rowe, T. 2004. Ceratosauria. In: Weishampel, D.B., Dodson, P., & Osmolska, H. (Eds.) The Dinosauria (2nd edition). Berkeley: University of California Press. Pp. 47-70.
3. ^ Sereno, P.C., Wilson, J.A., & Conrad, J.L. 2004. New dinosaurs link southern landmasses in the Mid-Cretaceous. Proceedings of the Royal Society of London: Biological Sciences 271: 1325-1330.
4. ^ Sampson, S.D., Witmer, L.M., Forster, C.A., Krause, D.A., O'Connor, P.M., Dodson, P., Ravoavy, F. 1998. Predatory dinosaur remains from Madagascar: implications for the Cretaceous biogeography of Gondwana. Science 280: 1048-1051.
5. ^ a b Lamanna, M.C., Martinez, R.D., & Smith, J.B. 2002. A definitive abelisaurid theropod dinosaur from the early Late Cretaceous of Patagonia. Journal of Vertebrate Paleontology. 22(1): 58-69.
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Abrictosaurus - Early Jurassic Perio, 200 mya. South Africa. 1.2m (4ft) long.
Abrictosaurus is a genus of heterodontosaurid dinosaur from the Early Jurassic Period of what is now southern Africa. It was a small bipedal herbivore or omnivore, approximately 1.2 meters (4 feet) long, and weighing less than 45 kilograms (100 pounds).
This dinosaur is known from the fossil remains of only two individuals, found in the Upper Elliot Formation of Qacha's Nek District in Lesotho and Cape Province in South Africa, respectively. The Upper Elliot is thought to date from the Hettangian and Sinemurian stages of the Early Jurassic Period, approximately 200 to 190 million years ago.[1] This formation is thought to preserve sand dunes as well as seasonal floodplains, in a semiarid environment with sporadic rainfall. Other dinosaurs found in this formation include the theropod Megapnosaurus, the sauropodomorph Massospondylus, as well as other heterodontosaurids like Heterodontosaurus and Lycorhinus. Remains of terrestrial crocodylomorphs, cynodonts and early mammals are also abundant.[2]
Heterodontosaurids like Abrictosaurus were small, early ornithischians, named for their markedly heterodont dentition. They are best-known for the large, canine-like tusks (often called caniniforms) in both upper and lower jaws. There were no teeth in the front of the jaws, where a hard beak was used to crop vegetation. There were three premaxillary teeth, with the first two small and conical and the third enlarged to form the upper caniniform, counterpart to the even larger lower caniniform, which was the first dentary tooth. In the upper jaw, a large gap (or diastema) accommodated the lower caniniform tooth and separated the premaxillary teeth from the wider chewing teeth of the maxilla. Similar teeth lined the remainder of the lower jaw.[2]
Abrictosaurus is usually considered the most basal member of the family Heterodontosauridae.[1][2] Lycorhinus and Heterodontosaurus both had high-crowned cheek teeth, which overlapped each other in the jaw, forming a continuous chewing surface analogous to those of Cretaceous hadrosaurids. Abrictosaurus had more widely-separated cheek teeth, with lower crowns, more similar to other early ornithischians. It has been suggested that Abrictosaurus lacked tusks and that this is another primitive feature.[3] However, caniniforms were clearly present on one of the two specimens of Abrictosaurus. The upper caniniform measured 10.5 millimeters (0.4 inches) high, while the lower reached 17 mm (0.67 in). These caniniforms were serrated only on the anterior surface, unlike those of Lycorhinus and Heterodontosaurus, which were serrated on both anterior and posterior edges.[4][5] Abrictosaurus also had smaller, less powerful forelimbs than Heterodontosaurus and one fewer phalanx bone in both the fourth and fifth digits of the forelimb.[6]
From Wikipedia, the free encyclopedia
1. ^ a b c Norman, D.B., Sues, H.-D., Witmer, L.M., & Coria, R.A. 2004. Basal Ornithopoda. In: Weishampel, D.B., Dodson, P., & Osmolska, H. (Eds.). The Dinosauria (2nd edition). Berkeley: University of California Press. Pp. 393-412.
2. ^ a b c d Weishampel, D.B. & Witmer, L.M. 1990. Heterodontosauridae. In: Weishampel, D.B., Dodson, P., and Osmolska, H. The Dinosauria (1st edition). Berkeley: University of California Press. Pp.486-497.
3. ^ Sereno, P.C. 1986. Phylogeny of the bird-hipped dinosaurs (Order Ornithischia). National Geographic Research 2: 234-256.
4. ^ a b Thulborn, R.A. 1970. The systematic position of the Triassic ornithischian dinosaur Lycorhinus angustidens. Zoological Journal of the Linnean Society 49: 235-245.
5. ^ a b Hopson, J.A. 1975. On the generic separation of the ornithischian dinosaurs Lycorhinus and Heterodontosaurus from the Stormberg Series (Upper Triassic) of South Africa. South African Journal of Science 71: 302-305.
6. ^ a b c Thulborn, R.A. 1974. A new heterodontosaurid dinosaur (Reptilia: Ornithischia) from the Upper Triassic Red Beds of Lesotho. Zoological Journal of the Linnean Society of London. 55: 151-175.
7. ^ Irmis, Randall B.; Parker, William G.; Nesbitt, Sterling J.; and Liu, Jun (2007). "Early ornithischian dinosaurs: the Triassic record". Historical Biology 19 (1): 3–22. doi:10.1080/08912960600719988.
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Abydosaurus -Lower - Middle Cretaceous, 150 mya, United States. 50ft long, 10-20 tons.
Abydosaurus is a genus of brachiosaurid sauropod dinosaur known from skull and postcranial material found in upper Lower Cretaceous rocks of northeastern Utah, United States.
It is of interest because it is one of the few sauropods known from skull material, with the first described complete skull for a Cretaceous sauropod from the Americas.[1] It is also notable for its narrow teeth, as earlier brachiosaurids had broader teeth.[1]
Abydosaurus is based on DINO 16488, a nearly complete skull and lower jaws with the first four neck vertebrae. Abundant skull and postcranial bones were found at the same site, including partial skulls from three additional individuals, a partial hip and associated tail vertebrae, a shoulder blade, an upper arm bone, and hand bones. These fossils were found in a sandstone bed at the base of the Mussentuchit Member of the Cedar Mountain Formation, near the old visitor center of Dinosaur National Monument.
Although Abydosaurus lived some 45 million years after Giraffatitan, the skulls of these two genera are similar except for the narrower, sharper teeth and smaller nose of Abydosaurus. Abydosaurus can be differentiated from all other sauropods, including Giraffatitan, by subtle features of the nasal and maxillary bones, its relatively small external nares (nostrils), and some features of the teeth.[1]
From Wikipedia, the free encyclopedia
1. ^ a b c d e f Chure, Daniel; Britt, Brooks; Whitlock, John A.; and Wilson, Jeffrey A. (2010). "First complete sauropod dinosaur skull from the Cretaceous of the Americas and the evolution of sauropod dentition". Naturwissenschaften 97 (4): 379–391. doi:10.1007/s00114-010-0650-6. PMID 20179896. PMC 2841758. http://www.springerlink.com/content/lpn30h8tx2231223/fulltext.pdf.
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Acanthopholis - Middle Cretaceous, 110-100 mya. Western Europe, 13ft long.
Acanthopholis, meaning "spiny scales" is a genus of ankylosaurid dinosaur in the family Nodosauridae that lived during the Early Cretaceous Period (Albian to Cenomanian stages) around 100 million years ago. The dinosaur's name refers to its armour (Greek akantha meaning 'spine' or 'thorn' and pholis meaning 'scale'). Acanthopholis's armour consisted of oval plates set almost horizontally into the skin, with spikes protruding from the neck and shoulder area, along the spine. Acanthopholis was quadrupedal and herbivorous. Its size has been estimated to be in the range of 3 to 5.5 meters (10 to 18 ft) long and approximately 380 kilograms (840 lb) in weight.
A find of a braincase and some postcranial elements was discovered in England in 1867, and was named Acanthopholis horridus by Thomas Huxley. Acanthopholis is an invalid name in some sources, which state that not enough information has been collected to tell that the find is anything more than a nodosaur.
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Acanthostega - Devonian, 365 mya, Greenland.
It had eight digits on each hand (the number of digits on the feet is unclear) linked by webbing, it lacked wrists, and was generally poorly adapted to come onto land. Acanthostega also had a remarkably fish-like shoulder and forelimb.[2] The front foot of Acanthostega could not bend forward at the elbow, and thus could not be brought into a weight bearing position, appearing to be more suitable for paddling or for holding on to aquatic plants. It had lungs, but its ribs were too short to give support to its chest cavity out of water, and it also had gills which were internal and covered like those of fish, not external and naked like those of some modern amphibians which are almost wholly aquatic.[1] Acanthostega is the first tetrapod to show the shift in locomotory dominance from the pectoral to pelvic girdle. There are many morphological changes that allowed the pelvic girdle of Acanthostega to become a weight-bearing structure. In more ancestral states the two sides of the girdle were not attached. In Acanthostega there in contact between the two dies and fusion of the girdle with the sacral rib of the vertebral column. These fusions would have made the pelvic region more powerful and equipped to counter the force of gravity when not supported by the buoyancy of and aquatic environment[3].
Therefore, paleontologists surmise that it probably lived in shallow, weed-choked swamps, the legs having evolved for some other purpose than walking on land. Jennifer A. Clack interprets this as showing that this was primarily an aquatic creature descended from fish that had never left the sea, and that tetrapods had evolved features which later proved useful for terrestrial life, rather than crawling onto land and then gaining legs and feet as had previously been surmised. At that period, for the first time, deciduous plants were flourishing and annually shedding leaves into the water, attracting small prey into warm oxygen-poor shallows that were difficult for larger fish to swim in. Clack remarks on how the lower jaw of Acanthostega shows a change from the jaws of fish which have two rows of teeth, with a large number of small teeth in the outer row, and two large fangs and some small teeth in the inner row. It differs, having a small number of larger teeth in the outer row and smaller teeth in the inner row, and she suggests that this change probably went with a shift in early tetrapods from feeding exclusively in water to feeding with the head above water or on land.[1]
Research based on analysis of the suture morphology in its skull indicates that the species may have bitten directly on prey at or near the water's edge. Markey and Marshall compared the skull with the skulls of fish, which use suction feeding as the primary method of prey capture, and creatures known to have used the direct biting on prey typical of terrestrial animals. Their results indicate that Acanthostega was adapted for what they call terrestrial-style feeding, strongly supporting the hypothesis that the terrestrial mode of feeding first emerged in aquatic animals. If correct, this shows an animal specialized for hunting and living in shallow waters in the line between land and water.[4]
From Wikipedia, the free encyclopedia
1. Jennifer A. Clack, Scientific American, Getting a Leg Up on Land Nov. 21, 2005.
2."Acanthostega gunneri," Devonian Times.
3.*Boisvert, C. A. 2005. The pelvic fin and girdle of Panderichthys and the origin of tetrapod locomotion. Nature 438: 1145-1147.
4. Terrestrial-style feeding in a very early aquatic tetrapod is supported by evidence from experimental analysis of suture morphology, Molly J. Markey and Charles R. Marshall, PNAS April 16, 2007. Retrieved 2007-07-18
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Achelousaurus - Late Cretaceous, 80-65 mya . North America. 6m (20ft) long.
Achelousaurus is a genus of centrosaurine ceratopsid dinosaur from the Late Cretaceous Period of what is now North America. It was a quadrupedal herbivore with a parrot-like beak, a rough boss (raised bony area) on the snout and two more behind the eyes, and two horns on the end of its long bony neck frill. With a total body length of 6 meters (20 feet), Achelousaurus was a medium-sized ceratopsian.
The genus and the one named species were both named by paleontologist Scott Sampson in 1995. The generic name Achelousaurus is a complex reference to Greek mythology. Achelous, an important Greek river deity, had one of his horns torn off by Hercules, in a mythological fight with the legendary hero. All three known skulls of Achelousaurus have rough bosses in the same places where other ceratopsians had horns, giving it the appearance of having had its horns ripped off. Achelous was also celebrated for his shapeshifting ability, just as Achelousaurus appears to combine features of other ceratopsian dinosaurs.
Early reports suggested that Achelousaurus represented a transitional form between ceratopsians with modified horns like Einiosaurus (with which A. horneri shares two horns on the end of the frill), and the derived, hornless Pachyrhinosaurus (Horner et al., 1992). While they may or may not form a direct line of descent, all three of these genera are at least closely related, and are often united in the tribe Pachyrhinosaurini, inside the subfamily Centrosaurinae and the family Ceratopsidae (Sampson, 1995; Dodson et al., 2004).
Achelousaurus is known from the U.S. state of Montana, in the Two Medicine Formation, which preserves sediments dated from the Campanian stage of the Late Cretaceous Period, between 83 and 74 million years ago. Achelousaurus was found in the highest levels of the formation, so it is probably closer to the end of that timeframe. Other dinosaurs found in this formation include Daspletosaurus, Bambiraptor, Euoplocephalus, Maiasaura, and Einiosaurus.
Scientists have so far recovered three skulls and some postcranial material from the Two Medicine, all housed at the Museum of the Rockies in Bozeman, Montana. The skull of a full-grown Achelousaurus (including the frill horns) is over 5 feet (1.6 meters) long.
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Achillobator - Late Cretaceous, 95-85 mya. Asia, 15ft long.
Achillobator is a genus of dromaeosaurid theropod dinosaur from the late Cretaceous Period of what is now Mongolia, about 90 million years ago. It was probably an active bipedal predator, hunting with the large sickle-shaped claw on the second toe of each hind foot. It was a large dromaeosaurid: the holotype and only known individual of Achillobator is estimated as 5 meters (16 ft) long.
The generic name comes from Achilles, a famous ancient Greek warrior of the Trojan War, and the Mongolian word bator ("warrior" or "hero"). It refers to the large Achilles tendon needed to use the sickle claw on the foot, which was the major combat organ of dromaeosaurids. The one species is named A. giganticus because it is much larger than most other dromaeosaurids.
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Acrocanthosaurus - Cretaceous, 110 mya, North America. 13m (43ft) long.
Acrocanthosaurus meaning 'high-spined lizard', is a genus of theropod dinosaur that existed in what is now North America during the Aptian and early Albian stages of the Early Cretaceous. Like most dinosaur genera, Acrocanthosaurus contains only a single species, A. atokensis. Its fossil remains are found mainly in the U.S. states of Oklahoma and Texas, although teeth attributed to Acrocanthosaurus have been found as far east as Maryland.
Acrocanthosaurus was a bipedal predator. As the name suggests, it is best known for the high neural spines on many of its vertebrae, which most likely supported a ridge of muscle over the animal's neck, back and hips. Acrocanthosaurus was one of the largest theropods, approaching 12 meters (40 ft) in length, and weighing up to 6.17 metric tons (6.8 short tons).[1] Large theropod footprints discovered in Texas may have been made by Acrocanthosaurus, although there is no direct association with skeletal remains.
Recent discoveries have elucidated many details of its anatomy, allowing for specialized studies focusing on its brain structure and forelimb function. However, there is still debate over its evolutionary relationships, with some scientists classifying it as an allosaurid, and others as a carcharodontosaurid. Acrocanthosaurus was the largest theropod in its ecosystem and likely an apex predator which possibly preyed on large sauropods and ornithopods.
From Wikipedia, the free encyclopedia
1. Bates, K.T., Manning, P.L., Hodgetts, D. and Sellers, W.I. (2009). "Estimating Mass Properties of Dinosaurs Using Laser Imaging and 3D Computer Modelling."
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Adamantisaurus - Information coming soon
Adasaurus - Information coming soon
Aegyptosaurus - Late Cretaceous, 95mya, Africa.
Aegyptosaurus meaning 'Egypt’s lizard', for the country in which it was discovered is a genus of sauropod dinosaur believed to have lived in what is now Africa, around 95 million years ago, during the mid- and late-Cretaceous Period (Albian to Cenomanian stages). Like most sauropods, it had a long neck and a small skull. The animal's long tail probably acted as a counterweight to its body mass. Aegyptosaurus was a close relative of Argentinosaurus, a much larger dinosaur found in South America.
Aegyptosaurus was described by German paleontologist Ernst Stromer in 1932.[1] Its fossils have been found in Egypt, Niger and in several different locations in the Sahara Desert. All known examples were discovered before 1939. The fossils were stored together in Munich, but were obliterated when an Allied bombing raid destroyed the museum where they were kept in 1944, during World War II.
It is possible that Aegyptosaurus was common prey for large predatory dinosaurs, such as Carcharodontosaurus and Spinosaurus.
From Wikipedia, the free encyclopedia
1. ^ Stromer, E. (1932a). Ergebnisse der Forschungsreisen Prof. E. Stromers in den Wüsten Ägyptens. II. Wirbeltierreste der Baharîje-Stufe (unterstes Cenoman). 11. Sauropoda. Abhandlungen der Bayerischen Akademie der Wissenschaften Mathematisch-naturwissenschaftliche Abteilung, Neue Folge, 10: 1-21.
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Aeolosaurus - Information coming soon
Aerosteon - Information coming soon
Afrovenator - Information coming soon
Agilisaurus - Middle Jurassic, 161 mya, Asia. 1.2m (4ft) lomg.
Agilisaurus is a genus of ornithischian dinosaur from the Middle Jurassic Period of what is now eastern Asia. Its tibia (lower leg bone) was longer than its femur (upper leg bone), which indicates that it was an extremely fast bipedal runner, using its long tail for balance, although it may have walked on all fours when browsing for food. It was a small herbivore, about 1.2 meters (4 feet) in length, and like all ornithischians, it had a beak-like structure on the ends of both upper and lower jaws to help it crop plant material.
There is one named species (A. louderbacki), named after Dr. George Louderback, an American geologist and the first to recognize dinosaur fossils from the Sichuan Province of China in 1915. Both genus and type species were named by Chinese paleontologist Peng Guangzhou in very brief fashion in 1990, then described in further detail by Peng in 1992.
A single complete skeleton of A. louderbacki is known to science, one of the most complete small ornithischian skeletons ever found. Only a few parts of its left fore limb and hind limb are missing, and those can be reconstructed from their counterparts on the right side.
This skeleton was actually discovered during the construction of the Zigong Dinosaur Museum, in which it is now housed. This museum features many dinosaurs recovered from the famous Dashanpu Quarry outside the city of Zigong, in the Chinese province of Sichuan, including Agilisaurus, as well as Xuanhanosaurus, Shunosaurus, and Huayangosaurus. This quarry preserves sediment from the Lower Shaximiao Formation (sometimes called "Xiashaximiao") which ranges from the Bathonian through Callovian stages of the Middle Jurassic Period, or from about 168 to 161 million years ago.
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Agustinia - Cretaceous, 100 - 116 mya, South America. 15m (3ft) long.
Agustinia is a genus of sauropod dinosaur from the Early Cretaceous Period of South America. Like all known sauropods, it was quadrupedal and herbivorous. Although some sauropods are known to have body armour, Agustinia's armour was unique even among sauropods. It had a series of wide, vertical spikes and plates down the center of its back, somewhat like the unrelated Stegosaurus. Aside from the armour, very little is known about the anatomy of Agustinia. A fibula (lower leg bone) has been recovered that is about 3 feet (895 mm) long. When compared to the same bone in related dinosaurs, this indicates that Agustinia may have been about 50 feet (15 meters) long.
The name Agustinia honors the discoverer of the specimen, Agustin Martinelli. This dinosaur was originally named in a 1998 abstract written by famous Argentine paleontologist Jose Bonaparte. The original generic name was Augustia, which, as it turned out, was already preoccupied by a beetle (see also: Megapnosaurus, Protognathosaurus). Bonaparte changed the name to Agustinia in a full paper published in 1999, which also introduced the family Agustiniidae. There is one named species (A. ligabuei), which is named in honour of Dr. Giancarlo Ligabue, a philanthropist who provided financial support to the expedition which recovered the remains.
Agustinia was recovered from the Lohan Cura Formation of Neuquen Province in Argentina, which is thought to date from the late Aptian to Albian stages of the Early Cretaceous Period, between 116 and 100 million years ago.
Only fragmentary remains are known. These include fragments of vertebrae from the back, hips, and tail regions of the spinal column, and 9 of the oddly-shaped plates or spikes which were attached to those vertebrae. Parts of the lower hind limb were also recovered: a fibula, tibia, and 5 metatarsals. A femur (thigh bone) was found at the site but was too fragmented to collect.
Because of its unusual features, Agustinia was originally assigned to its own family, Agustiniidae (Bonaparte, 1999). This family name has not come into wide acceptance. Agustinia is difficult to classify because of its fragmentary nature, and because it exhibits features of both diplodocoid and titanosaurian sauropods. Both groups are known in Early Cretaceous Argentina, so Agustinia most likely belongs to one or the other, but until more complete remains are found, it will be hard to know which one.
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Alamosaurus - Late Cretaceous, 65 mya, North America. 29m (61ft) long.
Alamosaurus, meaning "Alamo lizard", is a genus of titanosaurian sauropod dinosaur from the Late Cretaceous Period of what is now North America. It was a large quadrupedal herbivore, up to 21 metres (69 ft) in length[1], and around 35 tons in weight. [2] Alamosaurus, like other sauropods, had a long neck and a long tail, which may have ended in a whip-like structure.
Contrary to popular assertions, this dinosaur is not named after the Alamo in San Antonio, Texas, or the battle that was fought there. The holotype, or original specimen, was discovered in New Mexico and, at the time of its naming, Alamosaurus had not yet been found in Texas. Instead, the name Alamosaurus comes from Ojo Alamo, the former name for the geologic formation in which it was found (that part of the Ojo Alamo Formation has since been reassigned to Kirtland Shale) and which was, in turn, named after the nearby Ojo Alamo trading post. The term alamo itself is a Spanish word meaning "poplar" and is used for the local subspecies of cottonwood tree. The term saurus is derived from saura (σαυρα), Greek for "lizard" and is the most common suffix used in dinosaur names. There is one species (A. sanjuanensis), which is named after San Juan County, New Mexico, where the first remains were found. Both genus and species were named by Smithsonian paleontologist Charles W. Gilmore in 1922.
From Wikipedia, the free encyclopedia
1. Palmer, D., ed (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. p. 133. ISBN 1-84028-152-9.
2. http://www.natureandscience.org/research/alamosaurus.asp
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Alaskacephale - Late Campanian, 70 mya, Alaska.
Alaskacephale was a genus of pachycephalosaurid dinosaur that lived in the late Campanian stage of the Late Cretaceous (around 80 to 70 million years ago).
Alaskacephale was named by Robert Sullivan in 2006. The genus name refers to Alaska, where the fossil was found in the Prince Creek Formation. The species name, gangloffi, honors paleontologist Roland Gangloff. The only known specimen of A. gangloffi is the holotype, a nearly complete left squamosal with a characteristic array of polygonal nodes. The dimensions of this bone suggest that A. gangloffi was about half the size of Pachycephalosaurus wyomingensis or three quarters the size of Prenocephale prenes, and about the same size as Prenocephale edmontonensis and Prenocephale brevis (Gangloff et al. 2005).
The specimen was previously described by Gangloff et al. (2005) as an unnamed pachycephalosaurid, possibly a Pachycephalosaurus. Gangloff et al. described the squamosal as having a suture with the quadrate, a feature previously described only in Pachycephalosaurus. Sullivan (2006) opined that this "suture" is instead a breakage point in both Alaskacephale and Pachycephalosaurus, so it could not be used to unite the two taxa.
From Wikipedia, the free encyclopedia
* Gangloff, R.A., A.R. Fiorillo & D.W. Norton, 2005. The first pachycephalosaurine (Dinosauria) from the Paleo-Arctic of Alaska and its paleogeographic implications. Journal of Paleontology 79: 997-1001.
* Sullivan, R.M., 2006. A taxonomic review of the Pachycephalosauridae (Dinosauria: Ornithischia). New Mexico Museum of Natural History and Science Bulletin 35: 347-365.
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Albertonykus - Upper Cretaceous, Canada. 70 cm (2.5ft) Long.
Albertonykus (meaning "Alberta claw") is a genus of alvarezsaurid dinosaur from lower Maastrichtian-age (Upper Cretaceous) rocks of the Horseshoe Canyon Formation of Alberta, Canada. It is known from forelimb and hindlimb remains from multiple individuals. All but two of the specimens come from a bonebed dominated by Albertosaurus. Albertonykus is interpreted as having fed on wood-nesting termites because the forelimbs appear to be specialized for digging, but are too short for burrowing. Albertonykus is the earliest-known North American alvarezsaurid; isolated remains of alvarezsaurids are known from later rock units in Montana and Wyoming.[1]
The type species is A. borealis, described by Nicholas Longrich and Philip Currie in 2008. The specific name (borealis) means "north".[1]
Albertonykus is the smallest known alvarezsaurid ever discovered in North America, measuring only 70 centimeters (2.5 ft) in length.[4] Alvarezsaurs typically had slender hind legs, long rigid tails, and unusually short arms that were powerfully built to support a large claw. Although no skull bones of Albertonykus have been found, related animals from Mongolia show that they likely had long, slender snouts filled with tiny teeth similar to those of armadillos and anteaters.[3] It is likely that Albertonykus ate insects, using its large thumb claw to tear open rotten logs to find its prey.[4] As in other alvarezsaurs, the forelimbs of Albertonykus were specialized for digging, but were too short to permit burrowing.[6] Unfortunately at this time the skeleton of Albertonykus is not complete, but it Mongolian relatives give us a distinct idea of what the rest of the skeleton would have looked like.[3]
Possible prey items were evaluated and compared with the fossil record of social insects. Ants were not an important part of the ecosystem during the Cretaceous, and mound-building termites do not appear until the Eocene. This leaves the possibility that Albertonykus preyed on wood-nesting termites. This hypothesis was tested by examining petrified wood from the Horseshoe Canyon Formation, where Albertonykus was found. The wood found there frequently contains borings, which resemble those of termites.[6]
From Wikipedia, the free encyclopedia
1. Longrich, Nicholas R.; and Currie, Philip J. (2008). "Albertonykus borealis, a new alvarezsaur (Dinosauria: Theropoda) from the Early Maastrichtian of Alberta, Canada: Implications for the systematics and ecology of the Alvarezsauridae". Cretaceous Research online preprint: 239. doi:10.1016/j.cretres.2008.07.005.
2.Brian Switek, Smithsonian Magazine,http://dinosaur.smithsonianmag.com/2008/10/06/a-dinosaur-that-ate-termites-for-breakfast/
3. Nick Longrich, University of Calgary,http://www.ucalgary.ca/~longrich/Albertonykus%20borealis.html
4. Ken Than, National Geographic News,http://news.nationalgeographic.com/news/2008/09/080925-smallest-dinosaur.html
6.Longrich,DinoNews,http://www.dinodata.org/index.php?option=com_content&task=view&id=9909&Itemid=103
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Albertosaurus - Cretaceous, 70 mya, North America. 9m (30ft) long.
Albertosaurus meaning "Alberta lizard" is a genus of tyrannosaurid theropod dinosaur that lived in western North America during the Late Cretaceous Period, more than 70 million years ago. The type species, A. sarcophagus, was restricted in range to the modern-day Canadian province of Alberta, after which the genus is named. Scientists disagree on the content of the genus, with some recognizing Gorgosaurus libratus as a second species.
As a tyrannosaurid, Albertosaurus was a bipedal predator with tiny, two-fingered hands and a massive head with dozens of large, sharp teeth. It may have been at the top of the food chain in its local ecosystem. Although relatively large for a theropod, Albertosaurus was much smaller than its more famous relative Tyrannosaurus, probably weighing less than 2 metric tons.
From Wikipedia, the free encyclopedia
Since the first discovery in 1884, fossils of more than thirty individuals have been recovered, providing scientists with a more detailed knowledge of Albertosaurus anatomy than is available for most other tyrannosaurids. The discovery of 22 individuals at one site provides evidence of pack behavior and allows studies of ontogeny and population biology which are impossible with lesser-known dinosaurs.
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Aletopelta - Information coming soon
Alectrosaurus - Late Cretaceous, 80mya, Mongollia. 5.5m (17ft) long.
Alectrosaurus, meaning "unmarried lizard" is a genus of tyrannosauroid theropod dinosaur from the Late Cretaceous Period of Inner Mongolia. It was a bipedal carnivore with a body shape similar to its much larger relative, Tyrannosaurus rex. Alectrosaurus was much smaller though, most likely less than five meters (17 ft) long.
The generic name Alectrosaurus can also be translated as "alone lizard," and is derived from the Greek words alektros ("unmarried") and sauros ("lizard"). At the time of its discovery, it was unlike any other Asian carnivore known. There is one named species (A. olseni), which is named in honor of George Olsen, who discovered the first specimens in 1923 on the third American Museum of Natural History expedition to Mongolia. Both genus and species were named by American paleontologist Charles Gilmore in 1933.
The holotype (AMNH 6554), or original specimen, of Alectrosaurus was a hind limb discovered in the Iren Dabasu Formation of the Inner Mongolia Autonomous Region (Nei Mongol Zizhiqu) of the People's Republic of China.[1] The age of this geologic formation is not clear, but is commonly cited as the Campanian stage of the Late Cretaceous Period, about 83 to 74 million years ago.
More material, including comparable hind limb material as well as skull and shoulder elements, has been referred to Alectrosaurus. These fossils were found in the Bayan Shireh Formation of Outer Mongolia, a formation which is also of uncertain age.[2] It may possibly extend into the early Campanian, but recent estimates suggest it was deposited from Cenomanian through Santonian times.[3] Iren Dabasu and Bayan Shireh dinosaur faunas are similar, but van Itterbeecka et al. claimed that the Iren Dabasu is probably Campanian-Maastrichtian in age and possibly correlated with the Nemegt Formation, so it is not surprising that a species of Alectrosaurus would be found there.[4]
Furthermore, several more partial skeletons may have been found in both Inner and Outer Mongolia.[5] These remain undescribed as of early 2007.
From Wikipedia, the free encyclopedia
1. Gilmore, C.W. (1933). On the dinosaurian fauna of the Iren Dabasu Formation. Bulletin of the American Museum of Natural History 67:23-78.
2. Perle, A. (1977). [On the first finding of Alectrosaurus (Tyrannosauridae, Theropoda) in the Late Cretaceous of Mongolia.] Problemy Geologii Mongolii 3:104-113. [In Russian]
3. Hicks, J.F., Brinkman, D.L., Nichols, D.J., and Watabe, M. (1999). Paleomagnetic and palynological analyses of Albian to Santonian strata at Bayn Shireh, Burkhant, and Khuren Dukh, eastern Gobi Desert, Mongolia. Cretaceous Research 20(6): 829-850.
4. van Itterbeecka, J., Horne, D.J., Bultynck, P., and Vandenbergh, N. (2005). Stratigraphy and palaeoenvironment of the dinosaur-bearing Upper Cretaceous Iren Dabasu Formation, Inner Mongolia, People's Republic of China. Cretaceous Research 26:699-725.
5. Currie, P.J. (2001). Theropods from the Cretaceous of Mongolia. In: Benton, M.J., Shishkin, M.A., Unwin, D.M., and Kurochkin, E.N. (Eds.). The Age of Dinosaurs in Russia and Mongolia. Cambridge University Press:Cambridge, 434-455.
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Alioramus - Late Cretaceous, 70 mya, Asia. 5-6m (16-20ft) Long.
Alioramus meaning 'different branch' is a genus of tyrannosaurid theropod dinosaur from the Late Cretaceous period of Asia. The type A. remotus, is known from a partial skull and three metatarsals recovered from Mongolian sediments which were deposited in a humid floodplain between 70 and 65 million years ago. These remains were named and described by Russian paleontologist Sergei Kurzanov in 1976. A second species, A. altai, known from a much more complete skeleton, was named and described by Stephen L. Brusatte and colleagues in 2009. Its relationships to other tyrannosaurid genera are unclear, with some experts believing that Alioramus is closely related to the contemporaneous Tarbosaurus, or is a juvenile of that genus. However, the discovery of A. altai made it clear that the latter hypothesis was incorrect.
Alioramus was bipedal like most theropods, and its sharp teeth indicate that it was a carnivore. It was smaller than tyrannosaurids like Tarbosaurus and Tyrannosaurus, but its adult size is difficult to estimate since both species are known from juvenile or sub-adult remains. Alioramus is characterized by the row of five bony crests along the top of its snout, has more teeth than any other tyrannosaurid and its skull is lower than those of other tyrannosaurids.
Alioramus was estimated at 5 to 6 metres (16 to 20 ft) in length when originally described by Sergei Kurzanov in 1976.[1] Kurzanov, however, did not correct for lengthening of the skull by deformation during fossilization, which may indicate a shorter overall body length for this individual. If this specimen is a juvenile, then adult Alioramus would have reached greater lengths, but no confirmed adult specimens are known.[2]
The skull of A. remotus was approximately 45 centimetres (18 in) long.[3] In general, it is long and low, a shape typical of more basal tyrannosauroids and juveniles of larger tyrannosaurids. The premaxillary bones at the tip of the snout in Alioramus remotus have not been found, but are taller than wide in all tyrannosauroids for which they are known.[2] The nasal bones are fused and ornamented with a row of five irregular bony crests that protrude upwards from the midline, where the nasal bones are sutured together. These crests all measure more than 1 centimetre (0.39 in) tall.[1]
A. remotus skull diagram, known portions in white
At the back of the skull there is a transversely-oriented protrusion, called the nuchal crest, arising from the fused parietal bones, a feature shared with all tyrannosaurids. In Alioramus, the nuchal crest is greatly thickened, similarly to Tarbosaurus and Tyrannosaurus. Like the rest of the skull, the lower jaw of Alioramus was long and slender, another possible juvenile characteristic.[2] As in Tarbosaurus, a ridge on the outer surface of the angular bone of the lower jaw articulated with the rear of the dentary bone, locking the two bones together and removing much of the flexibility seen in other tyrannosaurids.[4] Other tyrannosaurids had four premaxillary teeth, D-shaped in cross section, on each side. Including 16 or 17 in each maxilla, and 18 in each dentary, Alioramus had 76 or 78 teeth, more than any other tyrannosaurid.[5]
The postcranial skeleton of Alioramus remotus is completely unknown except for three metatarsals, but the discovery of A. altai, which is known from substantially complete remains, has shed light on the morphology of the genus.[6] By inference from other tyrannosaurids, Alioramus moved about on two legs, which had proportions similar to those of ornithomimosaurs, with long tibiae and metatarsals in comparison to the femora. Like other tyrannosaurids, the forelimbs were very small and bore only two digits, although some tyrannosaurid specimens retained a vestigial third digit. A long tail would have balanced out the head and torso, putting the center of mass over the hips.[2]
From Wikipedia, the free encyclopedia
1. Kurzanov, Sergei M.. "A new carnosaur from the Late Cretaceous of Nogon-Tsav, Mongolia" (in Russian). The Joint Soviet-Mongolian Paleontological Expedition Transactions 3: 93–104.
2. Holtz, Thomas R. (2004). "Tyrannosauroidea". in Weishampel, David B.; Dodson, Peter; & Osmólska, Halszka (eds.). The Dinosauria (Second ed.). Berkeley: University of California Press. pp. 111–136. ISBN 0-520-24209-2.
3. Currie, Philip J. (2000). "Theropods from the Cretaceous of Mongolia". The Age of Dinosaurs in Russia and Mongolia. Cambridge: Cambridge University Press. pp. 434–455. ISBN 978-0521545822.
4. Hurum, Jørn H.; & Sabath, Karol. (2003). "Giant theropod dinosaurs from Asia and North America: Skulls of Tarbosaurus bataar and Tyrannosaurus rex compared". Acta Palaeontologica Polonica 48 (2): 161–190.
5. Currie, Philip J. (2003). "Cranial anatomy of tyrannosaurids from the Late Cretaceous of Alberta". Acta Palaeontologica Polonica 48 (2): 191–226.
6.Brusatte, Stephen L.; Carr, Thomas D.; Erickson, Gregory M.; Bever, Gabe S.; and Norell, Mark A. (2009). "A long-snouted, multihorned tyrannosaurid from the Late Cretaceous of Mongolia". Proceedings of the National Academy of Sciences of the United States of America online preprint (41): 17261–6. doi:10.1073/pnas.0906911106. PMID 19805035
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Allosaurus- Jurassic/Cretaceous, 140 mya, North America. 12m (40ft) long.
Allosaurus was a typical large theropod, having a massive skull on a short neck, a long tail and reduced forelimbs. Allosaurus fragilis, the best-known species, had an average length of 8.5 meters (28 ft),[1] with the largest definitive Allosaurus specimen (AMNH 680) estimated at 9.7 meters long (32 ft),[2] and an estimated weight of 2.3 metric tons (2.5 short tons).[2] In his 1976 monograph on Allosaurus, James Madsen mentioned a range of bone sizes which he interpreted to show a maximum length of 12 to 13 meters (40 to 43 ft).[3] As with 
dinosaurs in general, weight estimates are debatable, and since 1980 have ranged between 1500 kilograms (3300 lb), 1000 to 4000 kilograms (2200 to 8800 lb), and 1010 kilograms (2230 lb) for modal adult weight (not maximum).[4] John Foster, a specialist on the Morrison Formation, suggests that 1000 kg (2200 lb) is reasonable for large adults of A. fragilis, but that 700 kg (1500 lb) is a closer estimate for individuals represented by the average-sized thigh bones he has measured.[5] Using the subadult specimen nicknamed "Big Al", researchers using computer modelling arrived at a best estimate of 1,500 kilograms (3,300 lb) for the individual, but by varying parameters they found a range from approximately 1,400 kilograms (3,100 lb) to approximately 2,000 kilograms (4,400 lb).[6]
Several gigantic specimens have been attributed to Allosaurus, but may in fact belong to other genera. The closely related genus Saurophaganax (OMNH 1708) reached perhaps 10.9 meters (36 ft) in length,[2] and its single species has sometimes been included in the genus Allosaurus as Allosaurus maximus, though recent studies support it as a separate genus.[7] Another potential specimen of Allosaurus, once assigned to the genus Epanterias (AMNH 5767), may have measured 12.1 meters in length (40 ft).[2] A more recent discovery is a partial skeleton from the Peterson Quarry in Morrison rocks of New Mexico; this large allosaurid may be another individual of Saurophaganx.[8]
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From Wikipedia, the free encyclopedia
1. Glut, Donald F. (1997). "Allosaurus". Dinosaurs: The Encyclopedia. Jefferson, North Carolina: McFarland & Co. pp. 105–117. ISBN 0-89950-917-7.
2. Mortimer, Mickey (2003-07-21). "And the largest Theropod is...". The Dinosaur Mailing List. Retrieved 2007-09-08.
3. Madsen, James H., Jr. (1993) [1976]. Allosaurus fragilis: A Revised Osteology. Utah Geological Survey Bulletin 109 (2nd ed.). Salt Lake City: Utah Geological Survey.
4. Foster, John R. (2003). Paleoecological Analysis of the Vertebrate Fauna of the Morrison Formation (Upper Jurassic), Rocky Mountain Region, U.S.A.. New Mexico Museum of Natural History and Science Bulletin 23. Albuquerque: New Mexico Museum of Natural History and Science. p. 37.
5. Foster, John (2007). "Allosaurus fragilis". Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Bloomington, Indiana: Indiana University Press. pp. 170–176.
6. Bates, Karl T.; Falkingham, Peter L.; Breithaupt, Brent H.; Hodgetts, David; Sellers, William I.; and Manning, Phillip L. (2009). "How big was 'Big Al'? Quantifying the effect of soft tissue and osteological unknowns on mass predictions for Allosaurus (Dinosauria:Theropoda)". Palaeontologia Electronica 12 (3): unpaginated.. Retrieved 2009-12-13.
7. Chure, Daniel J. (2000). A new species of Allosaurus from the Morrison Formation of Dinosaur National Monument (Utah–Colorado) and a revision of the theropod family Allosauridae. Ph.D. dissertation. Columbia University.
8. Foster, John. 2007. Jurassic West: the Dinosaurs of the Morrison Formation and Their World. Bloomington, Indiana:Indiana University Press. p. 117.
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Altirhinus - Information coming soon
Alvarezsaurus - Late Cretaceous, 86 mya, Patagonia. 2m (7ft) long.
Alvarezsaurus "Alvarez's lizard" is a genus of small alvarezsaurid dinosaur from the Late Cretaceous period of Argentina, approximately 86 - 83 million years ago. Estimates suggest that it measured about 2 meters in length and weighed approximately 20 kg. It was found in the Bajo de la Carpa Formation and was named by paleontologist José Bonaparte in 1991 after the historian Don Gregorio Alvarez.
The type species is A. calvoi. It was bipedal, had a long tail and its leg structure suggests that it was a fast runner. It may have been insectivorous and was basal to better-known members of its family, such as Mononykus and Shuvuuia. It has been alternately classified with both non-avian theropod dinosaurs and early birds.
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Alxasaurus - Early Cretaceous, Inner Mongolia. 3.8m (12ft) long.
Alxasaurus, meaning Desert lizard" is a genus of therizinosauroid theropod dinosaur from the Early Cretaceous Period of Inner Mongolia. It is one of the earliest known members of the superfamily Therizinosauroidea, but it still possessed the body shape - including the long neck, short tail, and long hand claws - of later therizinosauroids. Like other members of this group, it was a bipedal herbivore with a large gut to process plant material. Several specimens are known and the largest was a little over 12 feet (3.8 m) long.
This dinosaur was first described and named by Canadian paleontologist Dale Russell and his Chinese colleague, Dong Zhiming, in a paper published in 1993. However, although the paper is technically included in the last issue of the 1993 volume of the Canadian Journal of Earth Sciences, this issue was actually released in the early weeks of 1994, so some sources list that as the year of publication instead.
Alxasaurus is named after the Alxa Desert of Inner Mongolia, also known as the "Alashan" desert, and the name also includes the Greek word sauros ("lizard"). Alxa (or Alashan) is also the name of the league, or administrative division, of the Inner Mongolia (Nei Mongol Zizhiqu) region of the People's Republic of China. The single known species (A. elesitaiensis) is named after Elesitai, a village found in this region, near which the fossil remains of Alxasaurus were located.
Five Alxasaurus skeletons were recovered from the Bayin Gobi Formation of Inner Mongolia, which dates to the Albian stage of the Early Cretaceous Period, or about 112 to 100 million years ago. The holotype, which is considered to exemplify the genus and species, is the largest and most complete of the five, consisting of the mandible (lower jaw) and some teeth, as well as many limb bones, ribs, and vertebrae, including all five sacral (hip) vertebrae and the first nineteen tail vertebrae. Together the skeletons represent most of the bones in the body aside from the skull.
While exhibiting many typical therizinosaur features in overall body shape and in the teeth, the skeleton of Alxasaurus also shows several features present in more typical theropods, and the discovery of this animal provided significant evidence that therizinosaurs were aberrant theropods. Specifically, the semilunate carpal bone of the wrist is found only in maniraptoran theropods, which also include oviraptorosaurs, dromaeosaurs, troodontids, and birds. Even more basal therizinosaurs such as Falcarius and the feathered Beipiaosaurus have since been discovered with more theropod features and have helped to solidify this arrangement. Alxasaurus is now thought to occupy a position between the early Beipiaosaurus and later therizinosaurs such as Erlikosaurus, Segnosaurus, and Therizinosaurus itself (Clark et al., 2004).
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Amargasaurus - Cretaceous, 130 mya, South America. 10m (33ft) long.
Amargasaurus is a genus of dicraeosaurid sauropod dinosaur from the Early Cretaceous Period (130-125 mya) of what is now South America. It was small for a sauropod, reaching 10 meters (33 feet) length. It would have been a quadrupedal herbivore with a long, low skull on the end of a long neck, much like its relative Dicraeosaurus. However, this dinosaur sported two parallel rows of tall spines down its neck and back, taller than in any other known sauropod. These spines have been reconstructed supporting skin sails, but the "skin sail" hypothesis was rejected by Gregory S. Paul in 2000.[1]
The name Amargasaurus was coined in 1991 by Argentine paleontologists Leonardo Salgado and José Bonaparte,[2] because its fossil remains were found alongside the La Amarga Arroyo in the Neuquén province of Argentina. La Amarga is also the name of a nearby town, as well as the geologic formation the remains were recovered from. The word amarga itself is Spanish for "bitter," while sauros is Greek for "lizard." The one named species (A. cazaui) is named in honour of the man who discovered the site, Dr. Luis Cazau, a geologist with the YPF oil company, which at the time was state-owned.
This site is located in the lower (older) sections of the La Amarga Formation, which dates to the Barremian through early Aptian stages of the Early Cretaceous Period, or around 130 to 120 million years ago.
Amargasaurus is known from a relatively complete skeleton from a single individual. This skeleton includes the back of the skull, and all vertebrae of the neck, back, and hips, as well as a bit of the tail. The right side of the shoulder girdle is also known, as are the left forelimb and hind limb, and the left ilium, a bone of the pelvis.
Vertebral spines
The most obvious feature of Amargasaurus' skeleton is the series of tall spines on the neck and back vertebrae. The spines are tallest on the neck, where they are paired in two parallel rows. These rows continue along the back, decreasing in height as they approach the hips. The lower back and sacral (hip) vertebrae feature only single spines, which are long but much shorter than those of the neck, comparable to other sauropods. These spines may have supported a pair of tall skin sails. Similar sails are seen in the unrelated dinosaurs Spinosaurus and Ouranosaurus, as well as the pelycosaurs Dimetrodon and Edaphosaurus. There are a variety of hypotheses for the function of these sails, including defense, communication (for mating purposes or for simple species recognition), or temperature regulation. However, their true function remains unknown.
Similar spines are found on the presacral vertebrae of Dicraeosaurus from Africa, although not nearly as tall.
From Wikipedia, the free encyclopedia
1. Paul, Gregory S. (2000) The Scientific American Book of Dinosaurs, p 94. St. Martin's Press. ISBN 0312262264.
2. Salgado L & Bonaparte JF. (1991). Un nuevo sauropodo Dicraeosauridae, Amargasaurus cazaui gen. et sp. nov., de la Provincia del Neuquén, Argentina. Ameghiniana 28: 333-346. [in Spanish]
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Ammosaurus - Information coming soon
Ampelosaurus - Late Cretaceous, 70mya, Europe. 15m (50ft) long.
Ampelosaurus, meaning "vine lizard" is a titanosaurian sauropod dinosaur hailing from the Late Cretaceous Period of what is now Europe. Like most sauropods, it would have had a long neck and tail but it also carried armor in the form of osteoderms on its back. This dinosaur would have stretched about 15 meters (50 feet) from snout to tail. Recent media attention has made Ampelosaurus arguably one of the most famous dinosaurs known from France.
French paleontologist Jean Le Loeuff first described and named this dinosaur in 1995. The generic name is derived from the Greek words ampelos ("vine") and sauros ("lizard"), because the original fossil remains were found near the Blanquette de Limoux vineyard in southern France. There is one named species (A. atacis), which is named after the nearby Aude River, which is called Atax in Latin.
Ampelosaurus was originally found near the commune of Campagne-sur-Aude in the Aude département of France. It was recovered in the lower levels of the Marnes Rouges Inférieures Formation, which belong to the early Maastrichtian epoch of the Late Cretaceous Period, or about 74 to 70 million years ago. These sediments represent an ancient floodplain with numerous river channels.
The first remains were found in a bonebed discovered in 1989, which produced numerous ribs and vertebrae from the back and tail, as well as many limb bones, but no skull material aside from one tooth. Four osteoderms of different sizes and shapes were also recovered from this bonebed. This material comes from several different individuals. Since 1989, more material has been uncovered in the same region of France, including a relatively complete skeleton with some elements of the skull and lower jaw (Le Loueff, 2005).
Characteristics of the tail vertebrae and the presence of osteoderms indicate that Ampelosaurus belongs to Lithostrotia, a group of derived titanosaurians which also includes Alamosaurus and Saltasaurus (Upchurch et al., 2004). However, this has not been shown conclusively as Ampelosaurus has never been included in a cladistic analysis.
A complete skeleton of Ampelosaurus can be seen at Dinosauria, a museum specialized in dinosaurs and situated in the same area where the skeleton was discovered.
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Amphicoelias - Information coming soon
Anatosaurus - Information coming soon
Anatotitan - Late Cretaceous, North America. 12m (38ft) long.
Anatotitan, meaning "large duck" is a genus of flat-headed or hadrosaurine hadrosaurid ornithopod dinosaur (a "duck-billed dinosaur") from the very end of the Cretaceous Period, in what is now North America. Remains of Anatotitan have been preserved in the Hell Creek and Lance Formations, which are dated to the late Maastrichtian stage of the Late Cretaceous Period, representing the last three million years before the extinction of the dinosaurs (68 to 65 million years ago). This dinosaur is known from at least six specimens pertaining to two species, discovered in the U.S. states of South Dakota and Montana. Several of these specimens are extremely complete skeletons with well-preserved skulls. It was a large animal, up to approximately 12 meters (39 ft) in length, with an extremely long and low skull. Anatotitan exhibits one of the most striking examples of the "duckbill" snout common to hadrosaurs. It has a long taxonomic history, including decades classified with the genera Anatosaurus, Diclonius, and Trachodon.
The skull and skeleton of Anatotitan are well-known. Edward Drinker Cope estimated the length of what is now the type specimen as about 12 meters (38 ft) long, with a skull 1.18 meters long (3.87 ft).[1] This estimate was later revised downward to a length of 8.8 meters (29 ft),[2] although to be fair a dozen vertebrae, the hips, and thigh bones had been carried away by a stream cutting through it, and the tip of the tail was incomplete.[3] A second skeleton currently exhibited next to the type, but in a standing posture, is estimated at 9.1 meters (30 ft) long, with its head 5.2 meters (17 ft) above the ground.[3] The hip height of this specimen is estimated as approximately 2.1 meters (7 ft).[4] Other sources have estimated the length of Anatotitan as approximately 12 meters (39 ft).[5] Anatotitan may have weighed about 3 metric tons (3.3 tons).[4]
The skull of Anatotitan is known for its long, wide muzzle. Cope compared it to that of a goose in side view, and to a short-billed spoonbill in top view.[1] The skull was longer and lower proportionally than in any other known hadrosaurid. The toothless portion of the anterior mandible* was relatively longer than in any hadrosaur.[6] The bones surrounding the large openings for the nostrils formed deep pockets around the openings. The eye sockets were rectangular and longer front to back than top to bottom, although this may have been exaggerated by postmortem crushing. The skull roof was flat and lacked a bony crest, and the quadrate bone that formed the articulation with the lower jaw was distinctly curved. The lower jaw was long and straight, lacking the downward curve seen in other hadrosaurids, and possessing a heavy ridge running its length. The predentary was wide and shovel-like.[7] The ridge on the lower jaw may have reinforced the long, slender jaw.[8]
As mounted, the vertebral column of Anatotitan includes twelve neck, twelve back, nine sacral, and thirty+ tail vertebrae.[7] The limb bones were longer and more lightly built than those of other hadrosaurids of comparable size. Anatotitan had a distinctive pelvis, based on the proportions and form of the pubis bone.[6] Anatotitan, like other hadrosaurids, could move both on two legs and on four legs. It probably preferred to forage for food on four legs, but ran on two.[9] Henry Fairfield Osborn used the skeletons in the American Museum of Natural History to portray both quadrupedal and bipedal stances for Anatotitan.[3]
From Wikipedia, the free encyclopedia
1. Cope, Edward D. (1883). "On the characters of the skull in the Hadrosauridae". Proceedings of the Philadelphia Academy of Natural Sciences 35: 97–107.
2. Lull, Richard Swann; and Wright, Nelda E. (1942). Hadrosaurian Dinosaurs of North America. Geological Society of America Special Paper 40. Geological Society of America. pp. 225.
3. Osborn, Henry Fairfield (1909). "The Upper Cretaceous iguanodont dinosaurs". Nature 81 (2075): 160–162. doi:10.1038/081160a0.
4. Glut, Donald F. (1997). "Anatotitan". Dinosaurs: The Encyclopedia. Jefferson, North Carolina: McFarland & Co. pp. 132–134. ISBN 0-89950-917-7.
5. Sues, Hans-Dieter (1997). "Ornithopods". in Farlow, James O., and Brett-Surman, Michael K. (eds.). The Complete Dinosaur. Bloomington: Indiana University Press. pp. 338. ISBN 0-253-33349-0.
6. Chapman, Ralph E.; and Brett-Surman, Michael K. (1990). "Morphometric observations on hadrosaurid ornithopods". in Carpenter, Kenneth, and Currie, Philip J. (eds.). Dinosaur Systematics: Perspectives and Approaches. Cambridge: Cambridge University Press. pp. 163–177. ISBN 0-521-43810-1.
7. Lull and Wright, Hadrosaurian Dinosaurs of North America, pp. 157-159.
8. Lull and Wright, Hadrosaurian Dinosaurs of North America, pp. 163-164.
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Anchiornis - Mid-Late Jurassic, 155 mya, China.
Anchiornis is a genus of small, feathered, troodontid dinosaur. The genus Anchiornis contains the type species Anchiornis huxleyi, named in honor of Thomas Henry Huxley, an early proponent of biological evolution, and the first to propose a close evolutionary relationship between birds and dinosaurs. The generic name Anchiornis means "near bird", and its describers cited it as important in filling a gap in the transition between the body plans of avian birds and non-avian dinosaurs.[1]
Anchiornis is a small, early troodontid dinosaur with a triangular skull bearing several details in common with other troodontids. Also like other troodontids, Anchiornis had very long legs, usually an indication that it was a strong runner (however, the extensive leg feathers indicate that this may be an vestigial trait, as running animals tend to have reduced, not increased, hair or feathers on their legs).[2] The forelimbs of Anchiornis were also very long, unusual among troodontids (which tend to be short-armed) but similar to dromaeosaurids and early birds, emphasizing its basal ("primitive") position among its relatives.
The first fossil was recovered from the Yaolugou locality, Jianchang County, western Liaoning, China; the second, at the Daxishan locality of the same area. The deposits are lake sediment, and are of uncertain age. Radiological measurements indicate an early Late Jurassic age for them, between 161 and 151 million years ago.[2]
While the first specimen of Anchiornis preserved only faint traces of feathers around the preserved portion of the body, the well-preserved second specimen showed nearly complete feather preservation, allowing researchers to identify the structure of the feathers and how they were distributed.
As in other early paravians such as Microraptor, Anchiornis had large wings, made up of pennaceous flight feathers attached to the arm and hand (as in modern birds) as well as flight feathers on the hind legs, forming an arrangement of fore and hind wings. The forewing of Anchiornis was composed of 11 primary feathers and 10 secondary feathers. Unlike Microraptor, the primary feathers in Anchiornis were about as long as the secondaries and formed a more rounded wing, with curved but symmetrical central vanes, a small and thin relative size, and rounded tips, all indicating poorer aerodynamic ability compared to its later relative. In Microraptor and Archaeopteryx, the longest forewing feathers were closest to the tip of the wing, making the wings appear long, narrow, and pointed. However, in Anchiornis, the longest wing feathers anchored near the wrist, making the wing broadest in the middle and tapering near the tip for a more rounded, less flight-adapted profile.[2]
The hind wings of Anchiornis were also shorter than those of Microraptor, and were made up of 12–13 flight feathers anchored to the tibia (lower leg) and 10–11 to the metatarsus (upper foot). Also unlike Microraptor, the hind wing feathers were longest closer to the body, with the foot feathers being short and directed downward, almost perpendicular to the foot bones.[2]
Unlike any other known Mesozoic dinosaur, the feet of Anchiornis (except for the claws) were completely covered in feathers (much shorter than the ones making up the hind wing).[2]
Two types of simpler, downy (plumaceous) feathers covered the rest of the body, as in Sinornithosaurus. Long downy feathers covered almost the entire head and neck, torso, upper legs,and the first half of the tail. The rest of the tail bore pennaceous tail feathers (rectrices).[2]
In 2010, a team of scientists examined numerous points among the feathers of an extremely well-preserved Anchiornis specimen to survey the distribution of melanosomes, the pigment cells that give feathers their color. By studying the types of melanosomes and comparing them with those of modern birds, the scientists were able to map the specific colors and patterning present on Anchiornis when it was alive. Though this technique had been used and described for isolated bird feathers and portions of other dinosaurs (such as the tail of Sinosauropteryx), Anchiornis became the first Mesozoic dinosaur for which almost the entire life coloration was known (note that the tail of this specimen was not preserved).[3]
Most of the body feathers of Anchiornis were gray and black. The crown of head feathers was mainly rufous with a gray base and front, and the face had rufous speckles among predominantly black head feathers. The fore and hind wing feathers were white with black tips. The coverts (shorter feathers covering the bases of the long wing feathers) were gray, contrasting the mainly white main wings. The larger coverts of the wing were also white with gray or black tips, forming rows of darker dots along mid-wing. These took the form of dark stripes or even rows of dots on the outer wing (primary feather coverts) but a more uneven array of speckles on the inner wing (secondary coverts). The shanks of the legs were gray other than the long hind wing feathers, and the feet and toes were black.[3]
Anchiornis is notable for its proportionally long forelimbs, which measured 80% of the total length of the hind limbs. This is similar to the condition in early avians such as Archaeopteryx, and the authors pointed out that long forelimbs are necessary for flight. Anchiornis also had a more avian wrist than other non-avialan theropods. The authors initially speculated that it would have been possible for Anchiornis to fly or glide. However, further finds showed that the wings of Anchiornis, while well-developed, were short when compared to later species like Microraptor, with relatively short primary feathers that had rounded, symmetrical tips, unlike the pointed, aerodynamically proportioned feathers of Microraptor.[2]
Anchiornis has hind leg proportions more like those of lower theropod dinosaurs than avialans, with long legs indicating a fast-running lifestyle. However, while long legs normally indicate a fast runner, the legs and even feet and toes of Anchiornis were covered in feathers, including long flight feathers similar to those in the hind wings of Microraptor, making it unlikely that Anchiornis was a capable ground runner.[2]
Like many modern birds, Anchiornis exhibited a complex pattern of coloration with different colors in speckled patterns across the body and wings, or "within- and among-feather plumage coloration." In modern birds, such color patterning is used in communication and display, either to members of the same species (e.g. for mating or territorial threat display) or to threaten and warn off competing or predatory species.[3]
From Wikipedia, the free encyclopedia
1. ^ Xu, X.; Zhao, Q.; Norell, M.; Sullivan, C.; Hone, D.; Erickson, G.; Wang, X.; Han, F. et al. (2009), "A new feathered maniraptoran dinosaur fossil that fills a morphological gap in avian origin", Chinese Science Bulletin 54: 430–435, doi:10.1007/s11434-009-0009-6 Abstract
2. ^ a b c d e f g h i j Hu, D; Hou, L.; Zhang, L. & Xu, X. (2009), "A pre-Archaeopteryx troodontid theropod from China with long feathers on the metatarsus", Nature 461 (7264): 640–643, doi:10.1038/nature08322, PMID 19794491
3. ^ a b c d Li, Q., Gao, K.-Q., Vinther, J., Shawkey, M.D., Clarke, J.A., D'Alba, L., Meng, Q., Briggs, D.E.G. and Prum, R.O. "Plumage color patterns of an extinct dinosaur." Science, 327(5971): 1369 - 1372. doi:10.1126/science.1186290 PMID 20133521
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Anchisaurus - Jurassic, 190 mya, North America, Africa. 2.4m (8ft) long.
Anchisaurus was a rather small dinosaur, with a length of just over 2 metres (6.6 ft), which helps explain why it was once mistaken for human bones.[2] It probably weighed around 27 kilograms (60 lb). However, Marsh's species A. major (also known as Ammosaurus) was larger, from 2.5 to 4 metres (8 ft 2 in to 13 ft 1 in) and some estimates give it a weight of up to 70 pounds (32 kg). All species of Anchisaurus lived during the Early Jurassic Period; more specifically, the Pliensbachian to Toarcian ages, 200 to 188 million years ago.
Digesting plant matter is a much more intensive biochemical process than digesting meat. This herbivore swallowed gastroliths (gizzard stones) to help break down the food in its stomach.[1] Herbivorous dinosaurs needed a huge gut. Since this had to be positioned in front of the pelvis, balancing on two legs became increasingly difficult, as dinosaurs became larger and they gradually evolved into the quadrupedal position that characterizes the later sauropods such as Diplodocus.[3] Prosauropods represented a middle phase between the earliest bipedal herbivores and the later giant sauropods. Although it was not itself a prosauropod, Anchisaurus was mostly typical of this group,[clarification needed] which flourished briefly during the late Triassic and early Jurassic. Anchisaurus teeth, used to rip food, were shaped like spoons.[1] It had fewer and more widely spaced teeth than true prosauropods, and as Peter Galton and Michael Cluver observed, narrower feet.[2] Anchisaurus would have spent most of its time on four legs but could have reared up on its hind legs to reach higher plants.
On the other hand, some paleontologists[who?] believe Anchisaurus may also have eaten meat, as it was in the transition between these two ultimately distinct groups. The teeth were blunt but with file-like edges, suggesting mostly plant matter was eaten and the jaw hinge was arranged in a way not entirely suited for tearing meat. Nevertheless, there is still some debate. The thumb had a large claw and the large eyes were not entirely on the side (as would be expected in an animal of a natural prey species).
As a quadrupedal/bipedal crossover, Anchisaurus had to have multi-purpose front legs. As 'hands', they could be turned inwards and be used for grasping. It had a simple reversible first 'finger', similar to a 'thumb'. As feet, the five toes could be placed flat against the floor and were strong at the ankle. This unspecialized design is typical of the early dinosaurs.
From Wikipedia, the free encyclopedia
1. Gaines, Richard M. (2001). Coelophysis. ABDO Publishing Company. pp. 14. ISBN 1-57765-488-9.
2. "Anchisaurus." In: Dodson, Peter & Britt, Brooks & Carpenter, Kenneth & Forster, Catherine A. & Gillette, David D. & Norell, Mark A. & Olshevsky, George & Parrish, J. Michael & Weishampel, David B. The Age of Dinosaurs. Publications International, LTD. p. 27. ISBN 0-7853-0443-6.
3. Palmer, D., ed (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. p. 122. ISBN 1-84028-152-9.
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Andesaurus - Cretaceous Period, South America, Andies.
Andesaurus is a genus of basal titanosaurian sauropod dinosaur which existed during the middle of the Cretaceous Period in South America. Like most sauropods, it would have had a small head on the end of a long neck and an equally long tail. Andesaurus was a very large sauropod, as were many others of its relatives, which included the largest animals ever to walk the Earth.
The only known material of Andesaurus is a partial skeleton consisting of a series of four vertebrae from the lower back, as well as 27 tail vertebrae, divided up into two series from separate parts of the tail. Elements of the pelvis were also discovered, including two ischia and a pubis bone, along with rib fragments and an incomplete humerus and femur.
These fossils were discovered in the Candeleros Formation, the oldest formation within the Neuquén Group of Neuquén Province, Argentina. This formation dates to the early Cenomanian stage of the Early Cretaceous Period, or about 100 to 97 million years ago. For the most part, the Candeleros represents an ancient braided river system, and besides Andesaurus, also contains fossils of theropods like Buitreraptor and the enormous Giganotosaurus, as well as other non-related sauropods such as Limaysaurus.
Several plesiomorphic (primitive) features characterize Andesaurus as the most basal known member of Titanosauria. In fact, this clade has been defined to contain Andesaurus, Saltasaurus, their most recent common ancestor, and all of its descendants (Salgado et al., 1997; Wilson & Upchurch, 2003). The most prominent plesiomorphy is the articulations between its tail vertebrae. In most derived titanosaurs, the tail vertebrae articulate with ball-and-socket joints, with the hollowed-out socket end on the front (procoelous caudal vertebrae), while in Andesaurus, both ends of the vertebrae are flat (amphiplatyan caudals), as seen in many non-titanosaurian sauropods. Andesaurus itself is only characterized by a single feature, the tall neural spines on top of its back vertebrae, and needs further study (Upchurch et al., 2004).
Some other basal titanosaurs from Argentina, including Argentinosaurus and Puertasaurus, were also sauropods of enormous size. The most derived group of titanosaurs, the Saltasauridae, included some of the smallest known sauropods, including Saltasaurus itself. Thus it is possible that the largest sizes were attained among the more basal members of the clade (Novas et al., 2005).
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Animantarx - Information coming soon
Angaturama - Early Cretaceous, Brazil.
Angaturama, meaning "noble, brave" is a genus of spinosaurid theropod from the Early Cretaceous Santana Formation of northeastern Brazil. The type specimen was discovered in a limestone nodule and consisted of the incomplete anterior portion of a skull. A description of the new species, A. limai by Alexander W.A. Kellner and Diogenes de A. Campos was published in February 1996. It was named after Angaturama, a protective spirit in the aboriginal Tupi Indian culture of Brazil, and paleontologist Murilo R. de Lima, who informed Kellner of the specimen in 1991. Later research uncovered 60% of the complete skeleton, allowing a replica to be made and mounted for exhibit at the Federal University-owned Rio de Janeiro National Museum.[1]Angaturama was diagnosed by the very strong lateral compression of the snout, and a thin sagittal crest (shape unknown) on top of the premaxillae. Fish may have formed a large part of its diet. However, a pterosaur fossil was found with an Angaturama tooth embedded in it, pointing to possible predation.
Angaturama was originally described as "the first remain of a dinosaur skull described from Brazil." However, as the paper describing Angaturama was in press, a partial spinosaurid skull from Brazil, bought from illegal fossil dealers, was published under the name Irritator. Many paleontologists suspect Angaturama and Irritator are the same dinosaur, in which case the name Irritator has priority.
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1. (Portuguese) O Estado de São Paulo, May 14, 2009, available at [1]; O Globo, May 15, 2009, abridgement available at [2]; university's announcement at [3] * Kellner, A.W.A. & D.A. Campos, 1996. First Early Cretaceous dinosaur from Brazil with comments on Spinosauridae. N. Jb. Geol. Paläont. Abh. 199 (2): 151-166.
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Anhanguera -Cretaceous. Brazil, UK. 5m (17ft) long.
Anhanguera, meaning "old devil" was a fish eater with a wingspan of 5 m (17 ft). It had a small, round crest on the front of its upper and lower jaw.
Ankylosaurus - Late Cretaceous, Canada, America, 68 mya. 9 meters (30 ft) long.
Ankylosaurus is a genus of ankylosaurid dinosaur, containing one species, A. magniventris. Fossils of Ankylosaurus are found in geologic formations dating to the very end of the Cretaceous Period in western North America.
Although a complete skeleton has not been discovered and several other dinosaurs are represented by more extensive fossil material, Ankylosaurus is often considered the archetypal armored dinosaur. Other ankylosaurids shared its well-known features - the heavily-armored body and massive bony tail club - but Ankylosaurus was the largest known member of the family.
In comparison with modern land animals the adult Ankylosaurus was very large. Some scientists have estimated a length of 9 meters (30 ft).[1] Another reconstruction suggests a significantly smaller size, at 6.25 m (20.5 ft) long, up to 1.5 m (5 ft) wide and about 1.7 m (5.5 ft) high at the hip.[2] Ankylosaurus may have weighed over 6,000 kilograms (13,000 lb).[3] The body shape was low-slung and quite wide. Ankylosaurus was quadrupedal, with the hind limbs longer than the forelimbs. Although its feet are still unknown, comparisons with other ankylosaurids suggest Ankylosaurus probably had five toes on each foot. The skull was low and triangular in shape, wider than it was long. The largest known skull 
measures 64.5 centimeters (25 in) long and 74.5 cm (29 in) wide.[2] Like other ankylosaurs, Ankylosaurus was herbivorous, with small, leaf-shaped teeth suitable for cropping vegetation. These teeth were smaller, relative to the body size, than in any other ankylosaurid species.[4] Ankylosaurus did not share the grinding tooth batteries of the contemporaneous ceratopsid and hadrosaurid dinosaurs, indicating that very little chewing occurred. Bones in the skull and other parts of the body were fused to increase their strength.[2
Armor
The most obvious feature of Ankylosaurus is its armor, consisting of massive knobs and plates of bone, known as osteoderms or scutes, embedded in the skin. Osteoderms are also found in the skin of crocodiles, armadillos and some lizards. The bone was probably overlain by a tough, horny layer of keratin. These osteoderms ranged greatly in size, from wide, flat plates to small, round nodules. The plates were aligned in regular horizontal rows down the animal's neck, back, and hips, with the many smaller nodules protecting the areas between the large plates. Smaller plates may have been arranged on the limbs and tail. Compared to the slightly more ancient ankylosaurid Euoplocephalus, the plates of Ankylosaurus were smooth in texture, without the high keels found on the armor of the contemporaneous nodosaurid Edmontonia. A row of flat, triangular spikes may have protruded laterally along each side of the tail. Tough, rounded scales protected the top of the skull, while four large pyramidal horns projected outwards from its rear corners.[2]
Tail club
The famous tail club of Ankylosaurus was also composed of several large osteoderms, which were fused to the last few tail vertebrae. It was heavy and supported by the last seven tail vertebrae, which interlocked to form a stiff rod at the base of the club. Thick tendons have been preserved, which attached to these vertebrae. These tendons were partially ossified (or bony) and were not very elastic, allowing great force to be transmitted to the end of the tail when it was swung. It seems to have been an active defensive weapon, capable of producing enough of a devastating impact to break the bones of an assailant.[2] A 2009 study showed that large tail knobs could generate sufficient force to break bone during impacts, but average and small knobs could not, and that tail swinging behavior is feasible in ankylosaurids, but it remains unknown whether the tail was used for interspecific defense, intraspecific combat, or both.
Environment
Ankylosaurus magniventris existed between 68 to 65.5 million years ago, in the final Maastrichtian stage of the Late Cretaceous Period, and was one of the dinosaurs to survive until the Cretaceous-Tertiary extinction event. The type specimen is from the Hell Creek Formation of Montana, while other specimens have been found in the Lance Formation of Wyoming and the Scollard Formation in Alberta, Canada, all of which date to the end of the Cretaceous.[1]
The Lance, Hell Creek and Scollard Formations represent different sections of the western shore of the shallow sea that divided western and eastern North America during the Cretaceous. They represent a broad coastal plain, extending westward from the seaway to the newly formed Rocky Mountains. These formations are composed largely of sandstone and mudstone, which have been attributed to floodplain environments.[7][8][9] The Hell Creek is the best studied of these ancient environments. At the time, this region was subtropical, with a warm and humid climate. Many plant species were supported, primarily angiosperms, with less common conifers, ferns and cycads. An abundance of fossil leaves found at dozens of different sites indicates that the area was largely forested by small trees.[10]
Fossils of Ankylosaurus are considerably rare in these sediments, compared to Edmontosaurus and the super-abundant Triceratops, which make up most of the large herbivore fauna. Another ankylosaur, Edmontonia, is also found in the same formations. However, Ankylosaurus and Edmontonia seem to have been separated both geographically and ecologically. Ankylosaurus had a wide muzzle, perhaps used for non-selective grazing and may have been limited to the upland regions, away from the coast, while Edmontonia had a narrower muzzle, indicating a more selective diet, and seems to have lived at lower elevations, closer to the coast.[2]
From Wikipedia, the free encyclopedia
1. Vickaryous, M.K., Maryanska, T., & Weishampel, D.B. 2004. Ankylosauria. In: Weishampel, D.B., Dodson, P., & Osmólska, H. (Eds.). The Dinosauria (2nd edition). Berkeley: University of California Press. Pp. 363-392.
2. Carpenter, K. 2004. Redescription of Ankylosaurus magniventris Brown 1908 (Ankylosauridae) from the Upper Cretaceous of the Western Interior of North America. Canadian Journal of Earth Sciences 41: 961–986.
3. Coombs, Walter P. (December 1978). "Theoretical Aspects of Cursorial Adaptations in Dinosaurs". The Quarterly Review of Biology 53: 393–418. doi:10.1086/410790.
4. Carpenter, Kenneth (2001). The Armored Dinosaurs. Indiana University Press. p. 255. ISBN 0253339642.
5. http://www.plosone.org/article/info:doi/10.1371/journal.pone.0006738
6. Thulborn, T. 1993. Mimicry in ankylosaurid dinosaurs. Record of the South Australian Museum 27: 151–158.
7. Lofgren, D.F. 1997. Hell Creek Formation. In: Currie, P.J. & Padian, K. (Eds.). The Encyclopedia of Dinosaurs. San Diego: Academic Press. Pp. 302-303.
8. Breithaupt, B.H. 1997. Lance Formation. In: Currie, P.J. & Padian, K. (Eds.). The Encyclopedia of Dinosaurs. San Diego: Academic Press. Pp. 394-395.
9. Eberth, D.A. 1997. Edmonton Group. In: Currie, P.J. & Padian, K. (Eds.). The Encyclopedia of Dinosaurs. San Diego: Academic Press. Pp. 199-204.
10. Johnson, K.R. 1997. Hell Creek Flora. In: Currie, P.J. & Padian, K. (Eds.). The Encyclopedia of Dinosaurs. San Diego: Academic Press. Pp. 300-302.
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Anserimimus - Late Cretaceous, 74-65 mya, Mongolia.
Anserimimus, meaning "goose mimic" is a genus of ornithomimid theropod dinosaur, from the Late Cretaceous Period of what is now Mongolia. It was a lanky, fast-running animal, possibly an omnivore. From what fossils are known, it probably closely resembled other ornithomimids, except for its more powerful forelimbs.
Mongolian paleontologist Rinchen Barsbold named Anserimimus in 1988, combining the Latin anser meaning 'goose' with the Greek mimos meaning 'mimic'. Anser is the generic name of several species of geese. Although Anserimimus does not specifically resemble a goose, ornithomimosaurs have traditionally been named after different types of birds, such as Struthiomimus ('ostrich mimic'), Gallimimus ('rooster mimic'), and Pelecanimimus ('pelican mimic'). The one known species of Anserimimus is called A. planinychus, from the Latin planus meaning 'flat', and the Ancient Greek onychos meaning 'claw', in reference to the peculiar flattened claws which characterize the genus.
Anserimimus is a member of the family Ornithomimidae, a group of derived ornithomimosaurians. Its closest relative may be Gallimimus (Kobayashi & Lu, 2003; Kobayashi & Barsbold, 2005). Other studies have been unable specifically to determine its relationships or those of any other ornithomimids (Ji et al., 2003; Makovicky et al., 2004).
Both Anserimimus and Gallimimus were recovered from the Nemegt Formation of Mongolia, albeit from different areas. Anserimimus was found in the Mongolian aimag, or province, of Bayankhongor during a joint Soviet-Mongolian expedition to the Gobi Desert, in the late 1970s. The Nemegt is thought to represent alluvial plains containing meandering rivers, dating from the Maastrichtian stage of the Late Cretaceous, or about 74 to 65 million years ago. Aside from Gallimimus, other theropods from this time and place include the gigantic Tarbosaurus and Deinocheirus, as well as smaller dromaeosaurids, oviraptorosaurs, troodontids, and birds. Herbivores are represented by the hadrosaurids Barsboldia and Saurolophus, the ankylosaurid Tarchia and several titanosaurian sauropods and pachycephalosaurians.
There is only a single specimen of Anserimimus, which consists of most of a forelimb and hind limb (including parts of the shoulder and pelvis) and one back vertebra. Limited information has been published on the anatomy of Anserimimus, as Barsbold did not describe most of these bones, instead focusing on only those with features that set Anserimimus apart from other ornithomimids. There are several key differences between it and other members of its family. The claws on the hand are long and straight (not curved), with the lower surface nearly flat. The forelimb is also built more powerfully than other ornithomimids, with large crests on the scapulocoracoid of the shoulder and humerus (upper arm bone), which provided attachment points for large arm muscles like the biceps.
The function of such a powerful 'arm', with straightened claws remains unknown. It may indicate a different diet or food-gathering strategy than other ornithomimids, although its diet is difficult to determine, since the animal's skull is unknown. Scientists have long hypothesized that ornithomimids, descended from carnivorous theropod ancestors, were actually omnivores or even herbivores (Osborn, 1916).
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Antarctopelta - Late Cretaceous, Antarctica. 4 m (13 feet) long.
Antarctopelta, meaning 'Antarctic shield' was a genus of ankylosaurian dinosaur with one known species, A. oliveroi, which lived in Antarctica during the Late Cretaceous Period. It was a medium-sized ankylosaur, reaching no more than 4 meters (13 feet) in length, and showed characteristics of two different families, making more precise classification difficult. The single known fossil specimen was discovered on James Ross Island in 1986, constituting the first dinosaur remains ever discovered on Antarctica, although it is the second dinosaur from the continent to be formally named.
Like other ankylosaurs, Antarctopelta oliveroi was a stocky, herbivorous quadruped protected by armor plates embedded in the skin. Although a complete skeleton has not been found, the species is estimated to have reached a maximum length of 4 meters (13 ft) from snout to tail tip. Very little of the skull is known, but all of the known skull fragments were heavily ossified for protection. One bone in particular, identified as a supraorbital, included a short spike which would have projected outwards over the eye. The leaf-shaped teeth are asymmetrical, with the majority of the denticles on the edge closest to the tip of the snout. These teeth are also proportionately large compared to those of other ankylosaurs, with the largest measuring 10 millimeters (0.4 inches) across.[1] This compares to the much larger North American Euoplocephalus, 6–7 m (20–23 ft) in body length, which had teeth averaging only 7.5 mm (0.3 in) across.[2]
Vertebrae from other sections of the tail were found. Although the tip of the tail did not fossilize, some of the smaller vertebrae recovered would have been situated near the end of the tail in life, and these were associated with ossified tendons on the upper and lower sides. In ankylosaurids, these tendons help to stiffen the end of the tail in support of a large, bony tail club. If such a club existed in Antarctopelta, it has yet to be discovered. Six different types of osteoderms were found along with the skeletal remains of Antarctopelta, but very few were articulated with the skeleton, so their placement on the body is largely speculative. They included the base of what would have been a large spike. Flat oblong plates resembled the ones that guarded the neck of the nodosaurid Edmontonia rugosidens. Large circular plates were found associated with smaller, polygonal nodules, perhaps forming a shield over the hips as seen in Sauropelta. Another type of osteoderm was oval-shaped with a keel running down the middle. A few examples of this fifth type were found ossified to the ribs, suggesting that they ran in rows along the flanks of the animal, a very typical pattern among ankylosaurs. The final group consisted mainly of small bony nodules which are often called ossicles, and were probably scattered throughout the body. Several ribs were also found with these ossicles attached.[1]
Antarctopelta shares several features with the nodosaurids, mainly in the teeth and armor, while the possibly-clubbed tail is far more similar to those of ankylosaurids. This mosaic of characters makes assignment to a specific family difficult. It has been designated as Ankylosauria incertae sedis, but has never been subjected to a phylogenetic analysis.[1]
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Antarctosaurus - Late Cretaceous, South America. 15ft long.
Antarctosaurus, meaning "southern lizard" is a genus of titanosaurian sauropod dinosaur from the Late Cretaceous Period of what is now South America. The type species, A. wichmannianus, was described by prolific German paleontologist Friedrich von Huene in 1929, who also described a second species in 1929. Three additional species of Antarctosaurus have been named since then. Later studies indicate that none of these pertain to Antarctosaurus.
Antarctosaurus was very large, even for a dinosaur. Scientists still have much to learn about Antarctosaurus, as a complete skeleton remains elusive.[1]
Antarctosaurus was a huge quadrupedal herbivore with a long neck and tail. It was possibly armoured. As Antarctosaurus is not known from a complete skeleton[1] and tail lengths are highly variable among sauropods, the true size of these animals is hard to extrapolate. The type species may have been over 60 feet (18 meters) long, and a second species may have been one of the largest land animals ever. Antarctosaurus may have been as tall as 15 feet at the shoulder.[1]
Remains of this dinosaur were first mentioned in print in 1916, although they were not fully described and named until a 1929 manuscript written by paleontologist Friedrich von Huene.[2] Antarctosaurus does not refer to the continent of Antarctica, since it was first found in Argentina, although it does have the same derivation, from the Greek words anti- meaning 'opposite of', arktos meaning 'north' and sauros meaning 'lizard'. The generic name refers to the animal's reptilian nature and its geographical location on a southern continent.
Von Huene used the name A. wichmannianus to describe a large assemblage of bones, which are now considered to come from the Anacleto Formation in Río Negro Province of Argentina, which is considered to be early Campanian in age or about 83-80 million years old. Several skull fragments were described, including a braincase and a mandible (lower jaw). Other bones referred to this dinosaur include neck and tail vertebrae, ribs, and numerous limb bones. One femur (thigh bone) is over 6 feet (1.85 meters) tall, which has been used to extrapolate a mass of about 34 metric tonnes, or nearly 75,000 pounds.[3]
These bones were for the most part not associated with each other but scattered throughout the formation. Consequently, many scientists believe that they may not all belong to the same type of animal. In particular, the very square lower jaw has frequently been suggested to belong to a rebbachisaurid sauropod similar to Nigersaurus.[4][5][6] However the jaw of Bonitasaura is similar in overall shape and is clearly associated with titanosaur skeletal remains, indicating that the lower jaw may belong to Antarctosaurus wichmannianus after all.[7] The back of the skull and the remainder of the skeleton are usually regarded as titanosaurian, although they do not necessarily belong to the same type of titanosaur. A. wichmannianus (minus the lower jaw) has been regarded as a lithostrotian, a group which includes armored titanosaurs, although no armor scutes were associated with its remains.[8]
From Wikipedia, the free encyclopedia
1. "Antarctosaurus." In: Dodson, Peter & Britt, Brooks & Carpenter, Kenneth & Forster, Catherine A. & Gillette, David D. & Norell, Mark A. & Olshevsky, George & Parrish, J. Michael & Weishampel, David B. The Age of Dinosaurs. Publications International, LTD. p. 125. ISBN 0-7853-0443-6.
2. von Huene, F. 1929. Los saurisquios y ornitisquios del Cretacéo Argentino. Anales del Museo de La Plata (series 3) 3: 1–196. [In Spanish]
3. Mazzetta, G.V., Christiansen, P., Fariña, R.A. 2004. Giants and Bizarres: Body Size of Some Southern South American Cretaceous Dinosaurs. Historical Biology. 16: 71-83.
4. Upchurch, P. 1999. The phylogenetic relationships of the Nemegtosauridae. Journal of Vertebrate Paleontology 19: 106–125.
5. Sereno, P.C., Beck, A.L., Dutheil, D.B., Larsson, H.C.E, Lyon, G.H., Moussa, B., Sadleir, R.W., Sidor, C.A., Varricchio, D.J., Wilson, G.P., Wilson, J.A. 1999. Cretaceous sauropods from the Sahara and the uneven rate of skeletal evolution among dinosaurs. Science 286: 1342–1347.
6. Wilson, J.A. 2002. Sauropod dinosaur phylogeny: critique and cladistic analysis. Zoological Journal of the Linnean Society 136: 217–276.
7. Apesteguía, S. 2004. Bonitasaura salgadoi gen. et sp. nov.: a beaked sauropod from the Late Cretaceous of Patagonia. Naturwissenschaften 91: 493–497.
8. Upchurch, P., Barrett, P.M, & Dodson, P. 2004. Sauropoda. In: Weishampel, D.B., Dodson, P., & Osmolska, H. (Eds.). The Dinosauria (2nd Edition). Berkeley: University of California Press. Pp. 259-322.
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Antetonitrus - Late Triassic, Southern Africa. 10m (33ft) long.
Antetonitrus, meaning "before the thunder" is the oldest known genus of sauropod dinosaur, living during the Late Triassic Period of southern Africa. It was a quadrupedal herbivore, like many of its later relatives, although it was far smaller than some of them. Antetonitrus was the largest animal in its environment, reaching up to 33 feet (10 m) long and weighing up to two tons, but still shows some primitive adaptations to use the forelimbs for grasping, instead of purely for weight support.
Adam Yates, an Australian expert on early sauropodomorphs, named Antetonitrus in a 2003 report co-authored by South African James Kitching. The name is derived from the Latin ante- ("before") and tonitrus ("thunder"), which refers to its existence, before other known sauropods, specifically Brontosaurus ("thunder lizard"). Brontosaurus is actually a junior synonym of Apatosaurus, but the name is still used in popular culture, and sauropods are sometimes called "thunder lizards" in vernacular terms. The one known species of Antetonitrus is called A. ingenipes, from the Latin ingens ("massive") and pes ("foot"), because its shows the beginning of the development of feet designed solely to support weight.
The fossils now known as Antetonitrus were actually discovered by Kitching in 1981 in the Free State of South Africa, and were stored in the Bernard Price Institute where they were labeled as Euskelosaurus. Yates recognized them as a separate taxon and published a description several years later. The holotype, or original specimen, consists of several vertebrae and numerous bones from both forelimb and hind limb, all presumed to be from one individual. Five more limb bones from another smaller individual were also referred to the genus.
Antetonitrus shows several features which appear to be approaching those of sauropods, but still retains some primitive features. Unlike most of its smaller and more lightly-built ancestors, Antetonitrus was primarily quadrupedal. Like sauropods, its forelimbs were much longer relative to its hind legs than earlier animals, and the wrist bones were broader and thicker to support more weight. However, the first digit of the hand, also called the "thumb" or pollex, was still twisted and flexible, capable of grasping against the hand. In more derived sauropods, the wrist bones are large and thick, arranged in such a way as to lock the hand into a permanently pronated position for full-time weight support, and the hand is incapable of grasping.
From Wikipedia, the free encyclopedia
* Buffetaut, E., Suteethorn, V., Cuny, G., Tong, H., Le Loeuff, J., Khansubha, S. & Jongautchariyakul, S. 2000. The earliest known sauropod dinosaur. Nature 407: 72–74.
* Yates, A.M. & Kitching, J.W. 2003. The earliest known sauropod dinosaur and the first steps towards sauropod locomotion. Proceedings of the Royal Society of London B: Biological Sciences 270: 1753-1758.
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Anurognathus - Late Jurassic, 150mya. Wing span 20 inches.
Anurognathus is a genus of small pterosaur that lived approximately 150 million years ago during the late Jurassic Period (Tithonian stage).
Anurognathus had a short head with pin-like teeth for catching insects and although it traditionally is ascribed to the long-tailed pterosaur group "Rhamphorhynchoidea", its tail was comparatively short, allowing it more maneuverability for hunting.[3] According to Döderlein the reduced tail of Anurognathus was similar to the pygostyle of modern birds.[2] Its more typical "rhamphorhynchoid" characters include its elongated fifth toe and short metacarpals and neck.[2] With an estimated wingspan of fifty centimetres (20 inches) and a nine centimetre long body (skull included), its weight was limited: in 2008 Mark Paul Witton estimated a mass of forty grammes for a specimen with a 35 centimetre wingspan.[4] The holotype was redescribed by Peter Wellnhofer in 1975.
Later a second, smaller, specimen was found, probably of a subadult individual. Its slab and counterslab are separated and both were sold to private collections; neither has an official registration. It was described by S. Christopher Bennet in 2007. This second exemplar is much more complete and better articulated. It shows impressions of a large part of the flight membrane and under UV-light remains of the muscles of the thigh and arm become visible. It provided new information on many points of the anatomy. The skull was shown to have been very short and broad, wider than long. It transpired that Wellnhofer had incorrectly reconstructed the skull in 1975, mistaking the large eye sockets for the fenestrae antorbitales, skull openings that in most pterosaurs are larger than the orbits but in Anurognathus are small and together with the nostrils placed at the front of the flat snout.
The eyes pointed forwards to a degree, providing some binocular vision. Most of the skull consisted of bone struts. The presumed pygostyle was absent; investigating the real nine tail vertebrae instead of impressions showed that they were unfused, though very reduced. The wing finger lacked the fourth phalanx. According to Bennett a membrane, visible near the shin, showed that the wing contacted the ankle and was thus rather short and broad. Bennett also restudied the holotype, interpreting bumps on the jaws as an indication that hairs forming a protruding bristle were present on the snout.[5]
Anurognathus was in 1937 assigned by Oskar Kuhn to the family Anurognathidae. In the modern clade Anurognathidae, Anurognathus is the sister taxon of the clade Asiaticognathidae, which contains the species Batrachognathus, Dendrorhynchoides and Jeholopterus.
According to Döderlein Anurognathus was, with its long wings, a swift flyer, surprising its prey, similar to the modern nightjar. Bennett however, infers from the discovery of the true shorter size of the wings, combined with the short tail, that it was a slower flying predator, specialised in hunting by manoeuvrability, its large eyes adapted to a crepuscular way of life. This would also be proven by a very large flexibility of the wing finger joints.
From Wikipedia, the free encyclopedia
1. ^ Döderlein, L. (1923). "Anurognathus Ammoni, ein neuer Flugsaurier". Sitzungsberichte der Mathematisch-Naturwissenschaftlichen Abteilung der Bayerischen Akademie der Wissenschaften zu München, 1923, 306-307.
2. ^ a b c "Anurognathus." In: Cranfield, Ingrid (ed.). The Illustrated Directory of Dinosaurs and Other Prehistoric Creatures. London: Salamander Books, Ltd. Pp. 292-295.
3. ^ a b Unwin, David M. (2006). The Pterosaurs: From Deep Time. New York: Pi Press. p. 246. ISBN ISBN 0-13-146308-X.
4. ^ Witton, M.P. (2008) "A new approach to determining pterosaur body mass and its implications for pterosaur flight". Zitteliania B28: 143-159
5. ^ Bennett, S. C. (2007). "A second specimen of the pterosaur Anurognathus ammoni", Paläontologische Zeitschrift, 81: 376-398
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Apatosaurus - Jurassic, 150 mya, North America. 21m (69ft) long.
Apatosaurus, including the popular but obsolete synonym Brontosaurus, is a genus of sauropod dinosaur that lived about 150 million years ago, during the Jurassic Period (Kimmeridgian and Tithonian ages). It was one of the largest land animals that ever existed, with an average length of 23 m (75 ft) and a mass of at least 23 metric tons (25 short tons). The composite term Apatosaurus comes from the Greek names apate meaning "deception"/"deceptive" and sauros meaning "lizard"; thus, "deceptive lizard". Othniel Charles Marsh gave it this name because he regarded the chevron bones as similar to those of some mosasaurs, members of a group of prehistoric marine lizards.
The cervical vertebrae were less elongated and more heavily constructed than those of Diplodocus and the bones of the leg were much stockier (despite being longer), implying a more robust animal. The tail was held above the ground during normal locomotion. Like most sauropods, Apatosaurus had only a single large claw on each forelimb, with the first three toes on the hind limb possessing claws.
Fossils of this animal have been found in Nine Mile Quarry and Bone Cabin Quarry in Wyoming and at sites in Colorado, Oklahoma and Utah, present in stratigraphic zones 2-6.[1]
Apatosaurus was a tremendously large long-necked quadrupedal animal with a long whip-like tail. Its forelimbs were slightly shorter than its hindlimbs. One measurement places the total length of Apatosaurus at 26 meters (85 ft) and its weight at 24-32 tons, roughly the weight of four elephants.[2]
The skull was small in comparison with the size of the animal. The jaws were lined with spatulate teeth, which resembled chisels, suited to an herbivorous diet.
From Wikipedia, the free encyclopedia
1. Foster, J. (2007). "Appendix." Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press. pp. 327-329.
2. Holtz, Thomas R. Jr. (2008) Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages Supplementary Information
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Appalachiosaurus - Late Cretaceous Period, North America. 7m (23ft) long.
Appalachiosaurus, meaning "Appalachian lizard" is a genus of tyrannosauroid theropod dinosaur from the Late Cretaceous Period of eastern North America. Like almost all theropods, it was a bipedal predator. Only a juvenile skeleton has been found, representing an animal over 7 meters (23 ft) long and weighing over 600 kilograms (1300 lb), which indicates an adult would have been even larger. This species is notable as the most completely known theropod from the eastern part of North America.
Fossils of Appalachiosaurus were found in central Alabama, from the Demopolis Chalk Formation. This formation dates to the middle of the Campanian stage of the Late Cretaceous, or around 77 million years ago.[1]
This dinosaur was named after the region of the central United States known as Appalachia, which also gave its name to the ancient island continent on which Appalachiosaurus lived. Both are named after the Appalachian Mountains. The generic name also includes the Greek word sauros ("lizard"), the most common suffix used in dinosaur names. There is one known species, A. montgomeriensis, which is named after Montgomery County in the U.S. state of Alabama. Both genus and species were named in 2005 by paleontologists Thomas Carr, 
Thomas Williamson, and David Schwimmer (who is not to be confused with the actor of the same name).
Appalachiosaurus is so far known from only partial remains, including parts of the skull and mandible (lower jaw), as well as several vertebrae, parts of the pelvis, and most of both hindlimbs. These remains are housed at the McWane Science Center in Birmingham, Alabama. There are several open sutures between bones of the skull, indicating that the animal was not an adult. Several elements are crushed, but the specimen is still informative and shows many unique characteristics, or apomorphies. Several of these apomorphies have been identified in the skull, and the claws of the feet show an unusual protrusion on the end closest to the body. A row of six low crests lines the top of the snout, similar to the Asian Alioramus, although most tyrannosaur species exhibit ornamentation to varying degrees on top of the snout. Appalachiosaurus is significantly different and more derived than another early tyrannosaur from eastern North America, Dryptosaurus.
The only known specimen Appalachiosaurus was complete enough to be included in phylogenetic analyses using cladistics. The first was performed before the animal had had even been named, and found Appalachiosaurus to be a member of the albertosaurine subfamily of Tyrannosauridae, which also includes Albertosaurus and Gorgosaurus.[2] The original description also included a cladistic analysis, finding A. montgomeriensis to be a basal tyrannosauroid outside of Tyrannosauridae.[1] However, Asian tyrannosaurs like Alioramus, and Alectrosaurus were excluded, as was Eotyrannus from England. Earlier tyrannosaurs such as Dilong and Guanlong had not been described at the time this analysis was performed. These exclusions may have a significant effect on the phylogeny. To date, no analysis has been published which includes all known tyrannosauroid taxa.
From Wikipedia, the free encyclopedia
1. ^ a b Carr, T.D., Williamson, T.E., & Schwimmer, D.R. (2005). "A new genus and species of tyrannosauroid from the Late Cretaceous (middle Campanian) Demopolis Formation of Alabama." Journal of Vertebrate Paleontology, 25(1): 119–143.
2. ^ Holtz, T.R. (2004). "Tyrannosauroidea." In: Weishampel, D.A., Dodson, P., & Osmolska, H. (Eds.). The Dinosauria (2nd Edition). Berkeley: University of California Press. Pp. 111–136.
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Aralosaurus - Information coming soon
Archaeoceratops - Information coming soon
Archaeopteryx - Jurassic, 150 mya, Europe. 60cm (2ft) long.
Archaeopteryx was roughly the size of a medium-sized modern-day bird, with broad wings that were rounded at the ends and a long tail compared to its body length. In all, Archaeopteryx could reach up to 500 millimeters (1.6 ft) in body length. Archaeopteryx feathers, although less documented than its other features, were very similar in structure and design to modern-day bird feathers.[6] However, despite the presence of numerous avian features,[7] Archaeopteryx had many theropod dinosaur characteristics. Unlike modern birds, Archaeopteryx had small teeth[6] as well as a long bony tail, features which Archaeopteryx shared with other dinosaurs of the time.[8]
Outline of bones in forelimbs of Deinonychus and Archaeopteryx. Both have two fingers and an opposed claw with very similar layout, although Archaeopteryx has thinner bones.
Comparison of the forelimbs of Deinonychus (left) and Archaeopteryx (right), one of many skeletal similarities between avians and dromaeosaurids.
Because it displays a number of features common to both birds and dinosaurs, Archaeopteryx has often been considered a link between them—possibly the first bird in its change from a land dweller to a bird.[6] In the 1970s, John Ostrom, following T. H. Huxley's lead in 1868, argued that birds evolved from theropod dinosaurs and Archaeopteryx was a critical piece of evidence for this argument; it preserves a number of avian features, such as a wishbone, flight feathers, wings and a partially reversed first toe, and a number of dinosaur and theropod features. For instance, it has a long ascending process of the ankle bone, interdental plates, an obturator process of the ischium, and long chevrons in the tail. In particular, Ostrom found that Archaeopteryx was remarkably similar to the theropod family Dromaeosauridae.[9][10][11][12][13][14][15][16][17][18][19][20]
The first remains of Archaeopteryx were discovered in 1861; just two years after Charles Darwin published On the Origin of Species. Archaeopteryx seemed to confirm Darwin's theories and has since become a key piece of evidence in the origin of birds, transitional fossils debate and the confirmation of evolution. Indeed, further research on dinosaurs from the Gobi Desert and China has since provided more evidence of a link between Archaeopteryx and the dinosaurs, such as the Chinese feathered dinosaurs. Archaeopteryx is close to the ancestry of modern birds, and it shows most of the features one would expect in an ancestral bird. However, it may not be the direct ancestor of living birds, and it is uncertain how much evolutionary divergence was already present among other birds at the time.
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From Wikipedia, the free encyclopedia
6. Lambert, David (1993). The Ultimate Dinosaur Book. New York: Dorling Kindersley. pp. 38–81. ISBN 1-56458-304-X.
7. Holtz, Thomas, Jr. (1995). "Archaeopteryxs Relationship With Modern Birds". Journal of Dinosaur Paleontology. http://www.dinosauria.com/jdp/archie/archie.htm. Retrieved 2007-03-01.
8. Palaeogeography, Palaeoclimatology, Palaeoecology 130 (1997) 275-292
9. Bühler, P. & Bock, W.J. (2002). Zur Archaeopteryx-Nomenklatur: Missverständnisse und Lösung. Journal of Ornithology. 143(3): 269–286. [Article in German, English abstract] doi:10.1046/j.1439-0361.2002.02006.x (HTML abstract)
10. Feduccia, A. (1993). Evidence from claw geometry indicating arboreal habits of Archaeopteryx. Science. 259(5096): 790–793.
11. Feduccia, A. & Tordoff, H.B. (1979). Feathers of Archaeopteryx: Asymmetric vanes indicate aerodynamic function. Science. 203(4384): 1021–1022.
12.Huxley T.H. (1868). On the animals which are most nearly intermediate between birds and reptiles. Geol. Mag. 5, 357–65; Annals & Magazine of Nat Hist 2, 66–75; Scientific Memoirs 3, 3–13.
13. Huxley T.H. (1868) Remarks upon Archaeopteryx lithographica. Proc Roy Soc 16, 243–48; Sci Memoirs 3, 340-45.
14. Huxley T.H. (1870) Further evidence of the affinity between the dinosaurian reptiles and birds. Quart J Geol Soc 26, 32–50; Sci Mem 3, 487–509.
15. Kennedy, Elaine (2000). Solnhofen Limestone: Home of Archaeopteryx. Geoscience Reports. 30: 1–4. Retrieved 2006-10-18.
16. Nedin, C. (1999). All About Archaeopteryx. talk.origins archive. Version of June 10, 2002; retrieved 2006-10-18.
17. Olson, S.L. & Feduccia, A. (1979). Flight capability and the pectoral girdle of Archaeopteryx. Nature. 278(5701). 247–248. doi:10.1038/278247a0 (HTML abstract)
18. Ostrom, J.H. (1976). Archaeopteryx and the origin of birds. Biol. J. Linn. Soc.. 8: 91–182.
19. Ostrom, J.H. (1985). Introduction to Archaeopteryx. In: Hecht, M.K.O.; Ostrom, J.H.; Viohl, G. & Wellnhofer, P. (eds.) The Beginnings of Birds: Proceedings of the International Archaeopteryx Conference: 9–20. Eichstätt, Freunde des Jura-Museums Eichstätt.
20. Owen, R. (1863). On the Archaeopteryx of Von Meyer, with a description of the fossil remains of a long-tailed species from the lithographic stone of Solnhofen. Phil. Trans. Roy. Soc. London. 153: 33–4
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Archaeornithomimus - Late Cretaceous, 80 mya. 3.3m (11 ft) long.
Archaeornithomimus (meaning "Before Bird Mimic") is a genus of ornithomimid dinosaur from late Cretaceous China, 80 million years ago. As its name suggests, this was the precursor to the more famous ornithomimid, Ornithomimus. Like other members of the ornithomimids, Archaeornithomimus was probably an omnivore, eating everything from small mammals, to plants and fruit, to eggs, and even hatchlings of other Asian dinosaurs. However, some scientists suggest that there is not enough evidence and fossil material to classify this dinosaur in any group or family.
Archaeornithomimus asiaticus on display at the Paleozoological Museum of China
The type species, A. asiaticus, was described by Dale Russell in 1972. Archaeornithomimus was about 3.3 meters (11 ft) long, and weighed up to 50 kilograms (110 lb).
Foot bones found in Maryland that were originally identified as Ornithomimus are now classified as belonging to another species, Archaeornithomimus affins, although other scientists say that they came from a small predator.
From Wikipedia, the free encyclopedia
* Archaeornithomimus in The Dinosaur Encyclopaedia, at Dino Russ's Lair
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Argentinosaurus - Cretaceous Period, 97-94 mya, Argentina. 30–35 m (98–115 ft) long.
Argentinosaurus is a genus of titanosaur sauropod dinosaur first discovered by Guillermo Heredia in Argentina. The generic name means "silver lizard", in reference to the country in which it was discovered ("Argentina" is derived from the Latin argentum). The dinosaur lived on the then-island continent of South America somewhere between 97 and 94 million years ago, during the mid Cretaceous Period.
Not much of Argentinosaurus has been recovered. The holotype included three anterior dorsal vertebrae, three posterior dorsal vertebrae, first to fifth sacrum vertebrae (only ventral sector the vertebral bodies), most of the sacral ribs of the right side, great part of a fragmented dorsal rib, and the right tibia. One vertebra had a length of 1.59 meters (spine to the ventral border) and the tibia was about 155 centimeters (58 inches).[1] Besides these, an incomplete femur (MLP-DP 46-VIII-21-3) is assigned to Argentinosaurus; this incomplete femur shaft is about 1.18 meters.[2] The proportions of these bones and comparisons with other sauropod relatives allow paleontologists to estimate the size of the animal.
An early reconstruction by Gregory S Paul estimated Argentinosaurus at between 30–35 metres (98–115 ft) in length and with a weight of up to 80–100 tonnes (88–110 short tons).[3] [4] Other estimates have compared the fragmentary material to relatively complete titanosaurs to help estimate the size of Argentinosaurus. In 2006 Carpenter used the more complete Saltasaurus as a guide and estimated Argentinosaurus at 30 metres (98 ft) in length.[5] An unpublished estimate used published reconstructions of Saltasaurus , Opisthocoelicaudia , and Rapetosaurus as guides and gave shorter length estimates of between 22–26 metres (72–85 ft).[6] Weight estimates are less common, but Mazzetta et al. (2004) provide a range of 60–88 tonnes (66–97 short tons), and consider 73 tonnes (80 short tons) to be the most likely, making it the heaviest sauropod known from good material.[2]
From Wikipedia, the free encyclopedia
1. ^ a b (Spanish)Bonaparte J, Coria R (1993). "Un nuevo y gigantesco sauropodo titanosaurio de la Formacion Rio Limay (Albiano-Cenomaniano) de la Provincia del Neuquen, Argentina". Ameghiniana 30 (3): 271–282.
2. ^ a b Mazzetta, Gerardo V.; Christiansen, Per; Fariña, Richard A. (2004). "Giants and Bizarres: Body Size of Some Southern South American Cretaceous Dinosaurs" (PDF). Historical Biology 65: 1–13. doi:10.1080/08912960410001715132. http://www.miketaylor.org.uk/tmp/papers/Mazzetta-et-al_04_SA-dino-body-size.pdf. Retrieved 2008-01-08.
3. ^ Paul, Gregory S. (Fall 1994). "Big Sauropods - Really, Really Big Sauropods". The Dinosaur Report. The Dinosaur Society. pp. 12–13.
4. ^ Paul, Gregory S. (1997). "Dinosaur models: the good, the bad, and using them to estimate the mass of dinosaurs". in Wolberg, D. L.; Stump, E.; Rosenberg, G. D.. DinoFest International Proceedings. The Academy of Natural Sciences. pp. 129–154.
5. ^ Carpenter, Kenneth (2006). "Biggest of the Big: A Critical Re-Evaluation of the Mega-Sauropod Amphicoelias fragillimus Cope, 1878". in Foster, John R.; Lucas, Spencer G.. Paleontology and Geology of the Upper Jurassic Morrison Formation. 36. New Mexico Museum of Natural History and Science Bulletin. pp. 131–138. https://scientists.dmns.org/sites/kencarpenter/PDFs%20of%20publications/Amphicoelias.pdf. Retrieved 2008-01-08.
6. ^ Mortimer, Mickey (2001-09-12). "Titanosaurs too Large?". Dinosaur Mailing List. http://dml.cmnh.org/2001Sep/msg00402.html. Retrieved 2009-01-08.
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Arrhinoceratops - Information coming soon
Aristonectes - Late Cretaceous, South America and Antarctica.
Aristonectes (meaning 'best swimmer') is an extinct genus of plesiosaur from the Late Cretaceous of what is now South America and Antarctica. The type species is Aristonectes parvidens, first named by Cabrera in 1941.
Aristonectes has been classified variously since the 1941 description, but a 2003 review of plesiosaurs conducted by Gasparini et al. found that Aristonectes was most closely related to elasmosaurid plesiosaurs like Elasmosaurus. A similar plesiosaur, Morturneria, may be a junior synonym of Aristonectes, the study found.
Aristonectes has been recently placed within its own family, along with Tatenectes, Kaiwhekea, and Kimmerosaurus, by O'Keefe and Street (2009). Aristonectids are the sister family of the polycotylid cryptoclidoids.
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Askeptosaurus - Italy and Switzerland, 2 metres (6.6 ft) long.
Askeptosaurus is an extinct genus of aquatic reptile related to the thalattosaurian group. Their remains have been found in Italy and Switzerland.
Askeptosaurus was a very thin, elongated creature, that probably swam like an eel. Its tail was very long, accounting for around half of the animal's total length of 2 metres (6.6 ft), and its webbed feet would have been well suited for steering itself through the water. Judging from its long jaws, it primarily ate fish.[1]
Askeptosaurus probably hunted in deep waters, because it had large eyes suited to conditions of low light. Like ichthyosaurs, it also had a protective bony ring around the eyes, which would have prevented them from collapsing under the immense water pressure of great depths.[1]
From Wikipedia, the free encyclopedia
1. ^ a b Palmer, D., ed (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. p. 83. ISBN 1-84028-152-9.
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Astrodon - Early Cretaceous, US. 15 to 18 m (50 to 60 ft) long.
Astrodon was a large genus of herbivorous sauropod dinosaur, related to Brachiosaurus, that lived in what is now the eastern United States during the Early Cretaceous period. Its fossils have been found in the Arundel Formation, which has been dated through palynomorphs to the Aptian-Albian boundary, about 112 million years ago.[1] Adults are estimated to have been more than 9 m (30 ft) high and 15 to 18 m (50 to 60 ft) long.
Two teeth were found in the Arundel Formation near Bladensburg, Maryland and named Astrodon in 1859 by Christopher Johnston. However, Johnston did not attach a specific epithet, so Joseph Leidy is credited with naming Astrodon johnstoni (the type species) in 1865. If Johnston had attached a scientific epithet, it would have been the second dinosaur identified in the United States.
In 1888, O.C. Marsh named some bones from the Arundel found near Muirkirk, Maryland Pleurocoelus nanus and P. altus. However, in 1921 Charles W. Gilmore argued that the name Astrodon had priority, a position that Carpenter and Tidwell (2005) accepted in the first in-depth description of this dinosaur. Interestingly, the majority of the bones of Astrodon are of juveniles. Astrodon is sometimes considered a synonym of Pleurocoelus, but the jury is still out on which name is correct. Carpenter and Tidwell therefore consider the two species named by Marsh, nanus and altus, as different growth stages of Astrodon johnsoni.[1]
From Wikipedia, the free encyclopedia
1. ^ a b Carpenter, Kenneth and Tidwell, Virginia (2005). "Reassessment of the Early Cretaceous Sauropod Astrodon johnsoni Leidy 1865 (Titanosauriformes)". in Carpenter, Kenneth and Tidswell, Virginia (ed.). Thunder Lizards: The Sauropodomorph Dinosaurs. Indiana University Press. pp. 38–77. ISBN 978-0-253-34542-4.
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Atlascopcosaurus - Information coming soon
Atrociraptor - Late Cretaceous, Alberta, Canada.
Atrociraptor, meaning "cruel thief" was a genus of dromaeosaurid dinosaur from the Late Cretaceous (Lower Maastrichtian stage) of Alberta, Canada. The type (and only) specimen was discovered in the Horseshoe Canyon Formation, near Drumheller, Alberta; it consists of parts of the upper and lower jaws and teeth. The skull appears to have been unusually short and tall. The teeth are relatively straight, but they emerge from the tooth sockets at an angle, resulting in a strongly raked row of teeth. A number of isolated teeth (previously referred to Saurornitholestes) have also been recovered from the Horseshoe Canyon Formation (Ryan et al. 1998); they can be recognized by their unusually large serrations.
Atrociraptor was about the size of a Bambiraptor. Atrociraptor is different from Bambiraptor and other velociraptorians via its isodont dentition and short deep snout. Atrociraptor is most closely related to Deinonychus, based on the large number of derived characters in both genera.
From Wikipedia, the free encyclopedia
* Currie, P. J. and D. J. Varicchio (2004). "A new dromaeosaurid from the Horseshoe Canyon Formation (Upper Cretaceous) of Alberta, Canada." Pp. 112–132 in P. J. Currie, E. B. Koppelhus, M. A. Shugar and J. L. Wright. (eds.), Feathered Dragons. Indianapolis: Indiana University Press.
* Ryan, M. J., P. J. Currie, et al. (1998). "Baby hadrosaurid material associated with an unusually high abundance of Troodon teeth from the Horseshoe Canyon Formation, Upper Cretaceous, Alberta, Canada." Gaia 16: 123-133.
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Attenborosaurus - Early Jurassic. UK.
Attenborosaurus is an extinct genus of plesiosaur from the Early Jurassic of Dorset, England. The type species is A. conybeari.
The species is named after David Attenborough.
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Aublysodon - Information coming soon
Aucasaurus- Late Cretaceous.
Aucasaurus was a genus of medium-sized theropod dinosaur from Argentina that lived during the late cretaceous. It was smaller than the related Carnotaurus, although more derived in some ways, such as its extremely reduced arms and almost total lack of fingers. The type skeleton is complete to the thirteenth caudal vertebra, and so is relatively well understood, and is the most complete abelisaurid yet described. However, the skull is damaged, causing some paleontologists to speculate that it was involved in a fight shortly prior to death.
This dinosaur was featured in the Discovery Channel series Dinosaur Planet, where it was depicted as a pack hunter and ate the sauropod Saltasaurus. In the episode, the head injury discovered in the type specimen was interpreted as being crushed by a stumbling Saltasaurus.
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Australovenator - Early Cretaceous, Australia. 6 metres (20 ft) long.
Australovenator (meaning "southern hunter") is a genus of allosauroid theropod dinosaur from late Albian (Early Cretaceous)-age rocks of Australia. It is known from partial cranial and postcranial remains which were described in 2009 by Scott Hocknull and colleagues.
The ankles of Australovenator and Fukuiraptor are similar to the Australian talus bone known as NMVP 150070 that had previously been identified as belonging to Allosaurus sp., and it is likely that this bone represents Australovenator or a close relative of it.[1][3] Alternatively, this bone could belong to an abelisaur.[4]
Australovenator was found about 60 kilometres northwest of Winton, near Elderslie Station. It was recovered from the lower part of the Winton Formation, dated to the latest Albian. Also found at the site were the type specimen of the sauropod Diamantinasaurus, bivalves, fish, turtles, crocodilians, and plant fossils. The Winton Formation had a faunal assemblage including bivalves, gastropods, insects, the lungfish Metaceratodus, turtles, the crocodilian Isisfordia, pterosaurs, and several types of dinosaurs, such as the sauropods Diamantinasaurus and Wintonotitan, and unnamed ankylosaurians and hypsilophodonts. Plants known from the formation include ferns, ginkgoes, gymnosperms, and angiosperms.[1]
Australovenator was a medium-sized allosauroid.[1] According to Hocknull, it was 2 metres (6.6 ft) tall at the hip and 6 metres (20 ft) long. Because it was a lightweight predator, he coined it as the "cheetah of its time".[5] Like other carnosaurians, Australovenator would have been a bipedal carnivore.[6]
From Wikipedia, the free encyclopedia
1. ^ a b c d Hocknull, Scott A.; White, Matt A.; Tischler, Travis R.; Cook, Alex G.; Calleja, Naomi D.; Sloan, Trish; and Elliott, David A. (2009). "New mid-Cretaceous (latest Albian) dinosaurs from Winton, Queensland, Australia". PLoS ONE 4 (7): e6190. doi:10.1371/journal.pone.0006190. PMID 19584929.
2. ^ Benson, R.B.J., Carrano, M.T and Brusatte, S.L. (2010). "A new clade of archaic large-bodied predatory dinosaurs (Theropoda: Allosauroidea) that survived to the latest Mesozoic." Naturwissenschaften, 97(1):71–78. doi:10.1007/s00114-009-0614-x
3. ^ Molnar, Ralph E.; Flannery, Timothy F.; and Rich, Thomas H.V. (1981). "An allosaurid theropod dinosaur from the Early Cretaceous of Victoria, Australia". Alcheringa 5: 141–146. doi:10.1080/03115518108565427.
4. ^ Agnolin, F. L.; Ezcurra, M. D.; Pais, D. F.; and Salisbury, S. W. (2010). "A reappraisal of the Cretaceous non-avian dinosaur faunas from Australia and New Zealand: Evidence for their Gondwanan affinities". Journal of Systematic Palaeontology 8 (2): 257–300.
5. ^ Scientists discover 3 new Aussie dinosaurs. ABC News. July 3, 2009
6. ^ Holtz, Thomas R., Jr.; Molnar, Ralph E.; and Currie, Philip J. (2004). Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.). ed. The Dinosauria (2nd ed.). Berkeley: University of California Press. pp. 71–110. ISBN 0-520-24209-2.
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Austroraptor- Cretaceous, 70 mya, Argentina. 5 metres (16 ft) long.
Austroraptor ("Southern thief") was a genus of dromaeosaurid dinosaur that lived about 70 million years ago during the Cretaceous period in what is now modern Argentina. The type species for the genus, Austroraptor cabazai, was described in late 2008 by Fernando Novas of the Museo Argentino de Ciencias Naturales. The fossil specimen was discovered in the Late Cretaceous deposits located in the Río Negro Province of Argentina.[1] The species was named in honor of Alberto Cabaza, who founded the Museo Municipal de Lamarque where the specimen was partially studied.[2][3][4]
Considered large for a dromaeosaur, Austroraptor cabazai measured around 5 metres (16 ft) in length from head to tail. It is the largest dromaeosaur to be discovered in the Southern Hemisphere.[1] Particularly notable about the taxon were its relatively short forearms, much shorter in proportion compared to those of other members of its family. The relative length of its arms has caused Austroraptor to be compared to another, more famous short-armed dinosaur, Tyrannosaurus.[2]
From Wikipedia, the free encyclopedia
1. ^ a b c d e Novas, Fernando E.; Diego Pol, Juan I. Canale, Juan D. Porfiri and Jorge O. Calvo (2008-12-16). "A bizarre Cretaceous theropod dinosaur from Patagonia and the evolution of Gondwanan dromaeosaurids". Proceedings of the Royal Society B (The Royal Society) 276 (1659): 1101–7. doi:10.1098/rspb.2008.1554. PMID 19129109. PMC 2679073. http://journals.royalsociety.org/content/90n26424nr722374/. Retrieved 2008-12-18.
2. ^ a b "Researchers find short-armed raptor in Argentina". Yahoo! News. 2008-12-16. http://news.yahoo.com/s/nm/20081217/sc_nm/us_dinosaur_argentina_1. Retrieved 2008-12-16.
3. ^ Museo Argentino de Ciencias Naturales (2008-12-17). "Descubrimiento de un dinosaurio "raptor" gigante en el norte de Patagonia". Press release. http://www.macn.secyt.gov.ar/cont_Eventos/2008/12/eventop-12-04.php. Retrieved 2008-12-17.
4. ^ "New dinosaur species similar to T.rex is uncovered in Argentina". Science & Tech (the Daily Mail). 2008-12-17. http://www.dailymail.co.uk/sciencetech/article-1096383/New-dinosaur-species-similar-T-rex-uncovered-Argentina.html. Retrieved 2008-12-18.
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Avaceratops - Information coming soon
Avimimus - Cretaceous, 80 mya, Asia. 1.5m (5ft) long.
Avimimus was a small dinosaur with a length of 1.5 m (5 ft).[1] The skull was small compared to the body, though the brain[1] and eyes were large. The size of the bones which surrounded the brain and were dedicated to protecting it are large.[1] This is also consistent with the hypothesis that Avimimus had a proportionally large brain.[1]
As in the related Oviraptoridae and Caenagnathidae, the jaws of Avimimus formed a parrot-like beak, and lacked teeth. However, a series of toothlike projections along the tip of the premaxilla would have given the beak a serrated edge. The toothless beak of Avimimus suggests that it may have been an herbivore or omnivore. Kurzanov himself, however, believed that Avimimus was an insectivore.[1]
The foramen magnum, the hole allowing the spinal cord to connect with the brain, was proportionally large in Avimimus.[1] The occipital condyle, however, was small, further suggestive of the skull's relative lightness.[1] The neck itself was long and slender, and is composed of vertebrae are much more elongate than in other oviraptorosaurs. Unlike oviraptorids and caenagnathids, the back vertebrae lack openings for air sacs, suggesting that Avimimus is more primitive than these animals.
The forelimbs were relatively short. The bones of the hand were fused together, as in modern birds, and a ridge on the ulna (lower arm bone) was interpreted as an attachment point for feathers by Kurzanov.[1][2] Kurzanov, in 1987, also reported the presence of quill knobs,[1][3] and while Chiappe confirmed the presence of bumps on the ulna, their function remained unclear.[4] Kurzanov was so convinced they were attachment points for feathers that he concluded that Avimimus may have been capable of weak flight.[1] The presence of feathers is now widely accepted, but most paleontologists do not believe Avimimus could fly.[1]
The ilium was almost horizontally oriented, resulting in exceptionally broad hips. Little is known of the tail but the hip suggests that the tail was long. The legs were extremely long and slender, suggesting that Avimimus was a highly specialized runner. The proportions of the leg bones add further weight to the idea of Avimimus was quick on its feet.[1] The animal's shins were long in comparison with its thighs,[1] a trait common among cursorial animals. It also had three-toed feet with narrow pointed claws.
From Wikipedia, the free encyclopedia
1. Avimimus." In: Dodson, Peter & Britt, Brooks & Carpenter, Kenneth & Forster, Catherine A. & Gillette, David D. & Norell, Mark A. & Olshevsky, George & Parrish, J. Michael & Weishampel, David B. The Age of Dinosaurs. Publications International, LTD. p. 130.
2. Kurzanov, S.M. (1981). "An unusual theropod from the Upper Cretaceous of Mongolia Iskopayemyye pozvonochnyye Mongolii (Fossil Vertebrates of Mongolia)." Trudy Sovmestnay Sovetsko-Mongolskay Paleontologiyeskay Ekspeditsiy (Joint Soviet-Mongolian Paleontological Expedition), 15: 39-49. Nauka Moscow, 1981
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