Achillobator

Achillobator
	Live reconstruction of Achillobator giganticus
Temporal occurrence
	Upper Cretaceous ( Coniacium to Santonium )
	89.7 to 83.6 million years
Locations
	Mongolia , Dorno-Gobi-Aimag ( Bayan-Shireh-Formation );
Systematics
	Lizard dinosaur (Saurischia)
	Theropoda
	Deinonychosauria
	Dromaeosauridae
	Dromaeosaurinae
	Achillobator
Scientific name
	Achillobator
	Pearl , Norell , Clark , 1999
Art
	Achillobator giganticus;

Achillobator was a genus of carnivorous dinosaurs from the Dromaeosauridae group . The only species is Achillobator giganticus .

So far a fragmented skeleton is known that from the Upper Cretaceous of Mongolia comes. With a length of about five meters, Achillobator was one of the largest representatives of the Dromaeosauridae after the American Utahraptor .

features

Achillobator is estimated to be around 5 meters long and weigh around 350 kg. The large upper jaw (maxillary) indicates a relatively large head that was proportionally similar in size to that of the Carnosauria . There were 11 teeth on each side of the upper jaw, the total number of teeth is unknown. Both the anterior and posterior incisal edges of the teeth were serrated, but the denticles (teeth), like other dromaeosaurids, were larger on the posterior cutting edge than on the anterior.

The hind legs were relatively short and stocky. In contrast to all other dromaeosaurids, the thighbone (femur) was longer than the shinbone (tibia). The arms were long. As with most other dromaeosaurids, the caudal vertebrae were connected by long, rod-like vertebral processes, elongated post- and prezygapophyses, and chevron bones . The second toe of the foot shows the curved and greatly enlarged sickle claw typical of dromaeosaurids. From other Dromaeosauriden can be Achillobator through several primitive features in the construction of the pool distinguished: So that was pubis (pubic) proportional shorter and not bird-like rearwardly oriented as in other Dromaeosauriden but showed ventral down. In addition, the enlarged lower end of the pubic bone ( pubic boot ) was very large.

Systematics and chimera hypothesis

Achillobator was probably the closest related to Utahraptor and Dromaeosaurus . Together these genera form the Dromaeosaurinae, a subgroup of the Dromaeosauridae.

Burnham and colleagues (2000) suspect that the skeleton they found could be a chimera , which means that the bones belonged to more than one species. These researchers argue that the maxilla, ischium, pubic bone, and caudal vertebrae do not share features in common with other dromaeosaurids and thus likely come from a different animal. However, the foot claws found would actually belong to a dromaeosaurid, according to the researchers. Norell and Makovicky (2004) argue that the bones were found partially associated, suggesting that they belonged to the same individual. Nevertheless, these researchers note that especially the vertically aligned pubic bone and its greatly broadened lower end are very atypical for dromaeosaurids.

Find, history of discovery and naming

The only known skeleton was discovered in 1989 by Namsarai, an assistant paleontologist at the Mongolian Natural History Museum, during a Russian-Mongolian expedition. The site, the Burkhant locality, is 28.8 km southwest of the village of Dzun Bayan in the Mongolian Aimag Dorno-Gobi . The Burkhant site is a small find with only 100 m ² ; the achillobator skeleton is the only find so far. The sedimentary rocks that contained the skeleton belong stratigraphically to the Bayan Shireh Formation . Remains of hadrosaurids , ankylosaurs , sauropods and crocodiles have been found from other sites in this formation . The sediments come from the Upper Cretaceous and are probably between 89 and 84 million years old ( Coniacium to Santonium ). However, this age is uncertain.

The skeleton ( holotype , specimen number FR.MNUFR-15) was found articulated; however, the bones were no longer in the anatomical bond. The find includes a left upper jaw bone (maxillary), nine teeth, some cervical, dorsal and tail vertebrae, three V-shaped chevron bones, rib fragments, some isolated hand and foot bones, the right iliac bone , pubic bone and ischium , the left femur and the tibia and the left metatarsals 3 and 4.

Achillobator giganticus was scientifically described for the first time in 1999 by Altangerel Perle , Mark Norell and James Clark in a Mongolian journal . However, the description is based on a preliminary manuscript and was published without the knowledge of Clark and Norell. The name Achillobator giganticus means "gigantic Achilles hero" and is made up of " Achilles ", a hero of Greek mythology , and "bator", which means hero. The name suggests a suspected very strong tendon that sat on the second toe and allowed strong movements of the sickle claw.

literature

Perle Altangerel , Mark A. Norell , James M. Clark : A new maniraptoran theropod, Achillobator giganticus (Dromaeosauridae), from the Upper Cretaceous of Burkhant, Mongolia. Contribution no.101 of the Mongolian-American Museum Paleontological Project. Geology and Mineralogy Chair, National University of Mongolia, Ulan Bator 1999.

Web links

Achillobator: Theropod Puzzle ( Memento from May 6, 2011 in the Internet Archive ) (English)

Individual evidence

^ ^A ^b Alan H. Turner, Diego Pol, Julia A. Clarke, Gregory M. Erickson, Mark A. Norell: A Basal Dromaeosaurid and Size Evolution Preceding Avian Flight. In: Science . Vol. 317, No. 5843, 2007, pp. 1378-1381, doi : 10.1126 / science.1144066 , digitized version (PDF; 507.41 kB) , Supporting Online Material (PDF; 755.11 kB) .
↑ ^a ^b ^c Mark A. Norell, Peter J. Makovicky : Dromaeosauridae. In: David B. Weishampel , Peter Dodson , Halszka Osmólska (eds.): The Dinosauria . 2nd edition. University of California Press, Berkeley CA et al. 2004, ISBN 0-520-24209-2 , pp. 196-209.
↑ Nicholas R. Longrich, Philip J. Currie : A microraptorine (Dinosauria – Dromaeosauridae) from the Late Cretaceous of North America. In: Proceedings of the National Academy of Sciences of the United States of America . Vol. 106, No. 13, 2009, pp. 5002-5007, doi : 10.1073 / pnas.0811664106 .
↑ David A. Burnham, Kraig L. Derstler, Philip J. Currie, Robert T. Bakker , Zhonghe Zhou , John H. Ostrom : Remarkable New Birdlike Dinosaur (Theropoda: Maniraptora) from the Upper Cretaceous of Montana (= The University of Kansas Paleontological Contributions. No. 13, ISSN 0889-0420 ). The University of Kansas, Lawrence KS 2009, (digitized) .
↑ Ben Creisler: Dinosauria Translation and Pronunciation Guide. Archived from the original on July 9, 2011 ; Retrieved July 30, 2014 .

[Turner2007-1] A ^b Alan H. Turner, Diego Pol, Julia A. Clarke, Gregory M. Erickson, Mark A. Norell: A Basal Dromaeosaurid and Size Evolution Preceding Avian Flight. In: Science . Vol. 317, No. 5843, 2007, pp. 1378-1381, doi : 10.1126 / science.1144066 , digitized version (PDF; 507.41 kB) , Supporting Online Material (PDF; 755.11 kB) .

[dinosauria-2] Mark A. Norell, Peter J. Makovicky : Dromaeosauridae. In: David B. Weishampel , Peter Dodson , Halszka Osmólska (eds.): The Dinosauria . 2nd edition. University of California Press, Berkeley CA et al. 2004, ISBN 0-520-24209-2 , pp. 196-209.

[currie_09-3] Nicholas R. Longrich, Philip J. Currie : A microraptorine (Dinosauria – Dromaeosauridae) from the Late Cretaceous of North America. In: Proceedings of the National Academy of Sciences of the United States of America . Vol. 106, No. 13, 2009, pp. 5002-5007, doi : 10.1073 / pnas.0811664106 .

[bambiraptor-4] David A. Burnham, Kraig L. Derstler, Philip J. Currie, Robert T. Bakker , Zhonghe Zhou , John H. Ostrom : Remarkable New Birdlike Dinosaur (Theropoda: Maniraptora) from the Upper Cretaceous of Montana (= The University of Kansas Paleontological Contributions. No. 13, ISSN 0889-0420 ). The University of Kansas, Lawrence KS 2009, (digitized) .

[creisler-5] Ben Creisler: Dinosauria Translation and Pronunciation Guide. Archived from the original on July 9, 2011 ; Retrieved July 30, 2014 .