The anatomy of the syncervical of Auroraceratops (Ornithischia: Ceratopsia), the oldest known ceratopsian syncervical

Abstract

The Early Cretaceous basal neoceratopsian dinosaur Auroraceratops rugosus was described based on a single skull recovered from the Gonpoquan Basin in northwestern Gansu Province, China. The genus is now known from cranial and postcranial remains representing at least 80 individuals, many of which come from the neighboring Yujingzi Basin, with an age of Aptian to earliest Albian (126-115 Ma). Among the new material were four syncervicals, representing the phylogenetically and temporally earliest occurrence of a syncervical in Ceratopsia. The anatomy of the syncervical matches that described in leptoceratopsids and protoceratopsids, with the first segment formed from a small atlas centrum, a much larger atlantal intercentrum, and a splint-like, divided atlantal neural arch. The axis bears a large hatchet-shaped neural spine and facets for a double-headed cervical rib. The centra of the first three cervical vertebrae and the first two intercentra are fused, though the boundaries of the individual elements are discernable. The relatively early temporal and phylogenetic appearance of a syncervical supports recent work that shows that the syncervical of ceratopsians is unrelated to the larger head size and cranial ornamentation characteristic of later appearing ceratopsian clades.Citation for this article: Li, D., E. M. Morschhauser, H. You, and P. Dodson. 2019. The anatomy of the syncervical of Auroraceratops (Ornithischia: Ceratopsia), the oldest known ceratopsian syncervical; pp. 69–74 in Hailu You, Peter Dodson, and Eric Morschhauser (eds.), Auroraceratops rugosus (Ornithischia, Ceratopsia) from the Early Cretaceous of northwestern Gansu Province, China. Society of Vertebrate Paleontology Memoir 18. Journal of Vertebrate Paleontology 38(Supplement). DOI: 10.1080/02724634.2018.1510411.