Brevidentavis zhangi O’Connor et al., 2021 (new genus and species)
(Type specimen of Brevidentavis zhangi [A: original specimen; B: schematic illustration; C, D: lower jaws in cross section, visualized through CT scanning], from O’Connor et al., 2021)
Meaning of name: Brevidentavis = short-tooth bird; zhangi = for Zhang Xing [co-leader of the 2002 expedition that rediscovered the locality where the original fossil was found]
Age: Early Cretaceous (Aptian)
Where found: Xiagou Formation, Gansu, China
How much is known: Partial skull and several vertebrae of one individual.
Notes: Brevidentavis was a euornithean, a group including modern birds and some of their closest extinct relatives. A previous paper assigned the type specimen to Gansus, another euornithean known from the same locality. Many specimens of Gansus have been found, but a definite skull is unknown. However, the authors of a new study consider a different specimen from the Xiagou Formation to be a more likely candidate for the skull of Gansus and chose to give the type specimen of Brevidentavis a new genus.
Brevidentavis exhibits several unusual features for a bird-like dinosaur, including short, blunt teeth in the lower jaw that were set in a groove (instead of in sockets). Among euornitheans, teeth set in a groove are otherwise only known in Hesperornithes, a group of specialized diving forms. In fact, the authors’ analyses find Brevidentavis as a possible early hesperornithean. However, given that the teeth and jaws of Brevidentavis are otherwise very different from those of hesperornitheans, the authors express skepticism of this result.
The strange teeth of Brevidentavis were presumably adapted for some form of specialized feeding, though without more complete remains or direct evidence of diet, its ecology is difficult to determine. A dark object preserved near the type specimen may represent a pellet, a mass of indigestible material from the dinosaur’s previous meals, but it does not contain obvious traces of bones, scales, or other remains that would shed light on the diet of Brevidentavis.
Although Brevidentavis is clearly distinct from other Xiagou Formation euornitheans for which skull material is known, overlapping material has not been found for three previously-named euornitheans from the same locality, Changmaornis, Jiuquanornis, and Yumenornis. It is therefore conceivable that Brevidentavis might end up being representing the skull of one of these genera.
Reference: O'Connor, J.K., T.A. Stidham, J.D. Harris, M.C. Lamanna, A.M. Bailleul, H. Hu, M. Wang, and H. You. 2021. Avian skulls represent a diverse ornithuromorph fauna from the Lower Cretaceous Xiagou Formation, Gansu Province, China. Journal of Systematics and Evolution advance online publication. doi: 10.1111/jse.12823