[D] Jeyawati rugoculus [sG] [T]
McDonald, Wolfe, & Kirkland 2010
Cretaceous Late Turonian
Ornithischia Ornithopoda Hadrosauridae [Hadrosauroidae]
Moreno Hill Formation, MSM Locality No. 98–61, Catron County, New Mexico, US
MSM P4166, a specimen from the Moreno Hill Formation (middle Turonian) of New Mexico, is described as the holotype of a new genus and species of hadrosauroid dinosaur. Jeyawati rugoculus, gen. et sp. nov., is diagnosed by a rugose texture that covers the entire lateral surface of the postorbital and the presence of a large neurovascular foramen at the base of the jugal process of the postorbital, as well as a unique combination of characters. A preliminary phylogenetic analysis reveals that Jeyawati is a basal hadrosauroid more derived than Probactrosaurus, Eolambia, and Protohadros, but more basal than Shuangmiaosaurus, Bactrosaurus, and Telmatosaurus. Assessment of ontogenetic criteria indicates that MSM P4166 represents a subadult or adult individual. Even with the recognition of Jeyawati, Late Cretaceous hadrosauroid biogeography remains somewhat ambiguous because of the lack of material from the late Turonian–early Santonian in western North America.
MSM P4166, disarticulated partial skull and fragmentary postcranium of a single individual.
The generic name is derived from the Zuni verbjeya-/u (‘grind’) and the noun awati (‘mouth’); essentially, ‘grinding mouth,’ in reference to themastication mechanism evolved by hadrosauroids. Jeyawati should be pronounced ‘HEY-a-WAHTee.’ The gender is masculine. The specific name is derived from the Latin ruga (‘wrinkle’) and oculus (‘eye’), in reference to the rough texture of the lateral surface of the postorbital.
Lower member of the Moreno Hill Formation, middle Turonian, Upper Cretaceous; probably correlative to Collignoniceras woollgari ammonite zone (Wolfe and Kirkland, 1998; Molenaar et al., 2002).
MSM Locality No. 98–61, Catron County, New Mexico, U.S.A.
For genus and species by monotypy. Nonhadrosaurid hadrosauroid characterized by two autapomorphies: highly vascularized, rugose texture covering entire lateral surface of postorbital (from orbital rim to at least the base of squamosal process) and large neurovascular foramen at base of jugal process of postorbital. Also diagnosed by the following combination of characters: extremely slender dentary (rostrocaudal length/depth at midpoint ratio = 5.6), coronoid process with strong rostral expansion, high number (32) of tooth alveoli in dentary, caudal extent of dentary tooth row is even with apex of coronoid process, at least two replacement teeth per dentary alveolus, asymmetrical tooth crowns, reduced accessory ridge on either side of primary ridge on dentary tooth crowns, lack of accessory ridges on maxillary tooth crowns, and paraquadrate foramen present.