Yamaceratops dorngobiensis is a species and genus of basal ceratopsian; neoceratopsian dinosaur.
Description[]
Yamaceratops was a herbivore. It lived in the Cretaceous period and inhabited Asia. Its fossils have been found in places such as Dornogovi; Mongolia. Its first described in 2006. Yamaceratops is a Neoceratopsian from the Javkhlant Formation of Mongolia, dating back to the Santonian age of the Late Cretaceous, some time between 86 and 83 million years ago.
It was an intermediate Neoceratopsian, between basal forms and later derived ones such as the Leptoceratopsid group. The frill may have served as a platform for enlarged jaw muscles, indicating that the evolution of the frill in Neoceratopsians was not solely for display, but rather the divergence between Neoceratopsians and Psittacosaurid-grade Ceratopsians was driven by multiple external stimuli.
A new articulated skeleton of Yamaceratops dorngobiensis (MPC-D 100/553) from the Khugenetjavkhlant locality at the Shine Us Khudag (Javkhlant Formation, Santonian-Campanian) of the eastern Gobi Desert, Mongolia, which represents the first substantially complete skeleton and the first juvenile individual of this taxon. The specimen includes a nearly complete cranium and large portions of the vertebral column and appendicular skeleton. Its skull is about 2/3 the size of the holotype specimen, based on mandibular length. Its juvenile ontogenetic stage is confirmed by multiple indicators of skeletal and morphological immaturity known in ceratopsians, such as the long-grained surface texture on the long bones, the smooth external surface on the postorbital, open neurocentral sutures of all caudal vertebrae, a large orbit relative to the postorbital and jugal, the low angle of the lacrimal ventral ramus relative to the maxillary teeth row, narrow frontal, and straight ventral edge of the dentary. Osteohistological analysis of MPC-D 100/553 recovered three lines of arrested growth, implying around 3 years of age when it died, and verified this specimen’s immature ontogenetic stage.
The specimen adds a new autapomorphy of Yamaceratops, the anteroventral margin of the fungiform dorsal end of the lacrimal being excluded from the antorbital fossa. Furthermore, it shows a unique combination of diagnostic features of some other basal neoceratopsians: the ventrally hooked rostral bone as in Aquilops americanus and very tall middle caudal neural spines about or more than four times as high as the centrum as in Koreaceratops hwaseongensis, Montanoceratops cerorhynchus, and Protoceratops andrewsi.
References[]
- https://www.biodiversitylibrary.org/bibliography/169144
- https://a-dinosaur-a-day.com/post/154529596600/yamaceratops
- http://novataxa.blogspot.com/2022/04/yamaceratops.html
- https://peerj.com/articles/13176/
- https://www.researchgate.net/publication/272152558_Yamaceratops_Dorngobiensis_a_New_Primitive_Ceratopsian_Dinosauria_Ornithischia_from_the_Cretaceous_of_Mongolia