Adasaurus mongoliensis was a dromaeosaurid theropod dinosaur (commonly referred to as a “raptor“) which lived in Mongolia during the late Cretaceous Period about 70 million years ago. Fragmentary remains were found during the 1970s, and it was officially named and described in 1983 by the Mongolian paleontologist Rinchen Barsbold.
Two partial skeletons have been found. Due to the incompleteness of the finds, establishing its size is difficult. It’s believed that it may have reached 10-11 feet long, thus approaching Deinonychus in size. Examination of the few fossils which have been found show that Adasaurus was a very close relative of Velociraptor and would have looked very similar to it. However, one noticeable difference was the size of the “killer claws” on the feet. Those on Velociraptor were quite substantial in size, whereas the “killer claw” on Adasaurus was the same size as the other toe claws. This indicates that the two species likely had different hunting styles or different prey preferences.
You can see a photograph of the skull specimen IGM 100/20 mounted by clicking here:
http://theropoddatabase.blogspot.com/2012/08/adasaurus-skull.html.
Skull of Adasaurus mongoliensis (collection ID code: IGM 100/20). A) Right lateral view; B) Left lateral view; C) Posterior view; D) Dorsal view. Turner, Alan H; Makovicky, Peter J.; Norell, Mark (2012). “A review of dromaeosaurid systematics and paravian phylogeny”. Bulletin of the American Museum of Natural History, number 371 (August 17, 2012). Page 21.
https://www.researchgate.net/publication/274270291_A_Review_of_Dromaeosaurid_Systematics_and_Paravian_Phylogeny.
Right foot of Adasaurus mongoliensis (collection ID code: IGM 100/20). Note the unusually small “killer claw”, which distinguishes Adasaurus from other dromaeosaurid genera. Turner, Alan H; Makovicky, Peter J.; Norell, Mark (2012). “A review of dromaeosaurid systematics and paravian phylogeny”. Bulletin of the American Museum of Natural History, number 371 (August 17, 2012). Page 24.
https://www.researchgate.net/publication/274270291_A_Review_of_Dromaeosaurid_Systematics_and_Paravian_Phylogeny.
Adasaurus was just one of several feathered theropod dinosaurs which lived in Mongolia during the late Cretaceous Period about 70 million years ago. By that point, iconic late Cretaceous Mongolian dinosaurs like Protoceratops, Oviraptor, and Velociraptor had long gone extinct, and had been replaced by other dinosaur species. Adasaurus shared its habitat with the tyrannosaurs Alioramus and Tarbosaurus, the oviraptorosaur Conchoraptor, the alverezsaur Mononykus, the giant therizinosaur Therizinosaurus, the ornithomimosaurs Gallimimus and Deinocheirus, the hadrosaurs Saurolophus and Shangtungosaurus, the pachycephalosaur Homalocephale, and the ankylosaurs Tarchia and Saichania.
Below is an illustration of Adasaurus mongoliensis. The drawing was made with No.2, No.3 and colored pencils on printer paper. The coloration is based upon the Eurasian Bullfinch (Pyrrhula pyrrhula), the Eurasian Nuthatch (Sitta europaea), the Common Chaffinch (Fringilla coelebs), and the Ornate Hawk-Eagle (Spizaetus ornatus).
Adasaurus mongoliensis. © Jason R. Abdale (December 15, 2022).
Finally, here is an image of my drawing done to scale with a human figure to provide some perspective. Adasaurus was substantially larger than its relative Velociraptor, about the size of a wolf, and it would have been a formidable predator.
Keep your pencils (and claws) sharp, everyone.
Categories: Paleontology, Uncategorized
DINOSAURS AND BARBARIANS 
The size of the toe claw provides some very interesting questions to hunting habits. Do you have a hypothesis? It seems that the “ground hawk” idea that is popular nowadays might be unlikely, since the reduced claw size would make pouncing on and holding prey to the ground with one’s feet more difficult. Not impossible, but not specialized for this theorized behavior. Perhaps it filled a role similar to young tyrannosaurs or other small theropods? Rather than what appears to be a very specialized behavior we see in most “raptors”?
I wish I knew the answer. The unusually small size of the claw is intriguing, and considering that the “killer claws” on other raptors were much larger than this, I can’t help but think that Adasaurus decided to go down a different path compared to its relatives. A larger body size coupled with a small claw size suggests that it was using its physical weight to pin down its prey, but I admit that this is a pretty weak explanation, and even I’m not altogether convinced of it. I know that it’s very trite and unsatisfactory to say this, but we need more specimens (preferably complete ones) in order to get a better idea of how this animal lived its life.
Reblogged this on Lower Deck Science.