[D] Zhuchengceratops inexpectus [sG] [T]
Xu, Wang, Zhao, Sullivan, Chen 2010
Ornithischia Genasauria Cerapoda Marginocephalia Ceratopia [Leptoceratopidae]
Wangshi Series, Kugou, Zhucheng County, Shandong Province, China
The ceratopsians represent one of the last dinosaurian radiations. Traditionally the only universally accepted speciose clade within the group was the Ceratopidae. However, recent discoveries and phylogenetic analyses have led to the recognition of a new speciose clade, the Leptoceratopidae, which is predominantly known from the Upper Cretaceous of North America. Methodology/Principal Findings: Here we report a new leptoceratopid taxon, Zhuchengceratops inexpectus gen. et sp. nov., based on a partial, articulated skeleton recovered from the Upper Cretaceous Wangshi Group of Zhucheng, Shandong Province, China.
Although Zhuchengceratops is significantly different from other known leptoceratopids, it is recovered as a derived member of the group by our phylogenetic analysis. Furthermore, Zhuchengceratops exhibits several features previously unknown in leptoceratopids but seen in ceratopids and their close relatives, suggesting that the distribution of morphological features within ceratopians is more complex than previously realized.
The discovery of Zhuchengceratops increases both the taxonomic diversity and the morphological disparity of the Leptoceratopidae, providing further support for the hypothesis that this clade represents a successful radiation of horned dinosaurs in parallel with the Ceratopidae in the Late Cretaceous. This documents a surprising case of the coexistence and radiation of two closely-related lineages with contrasting suites of jaw and dental features that probably reflect adaptation to different food resources.
Genus name from Zhucheng (the county that includes the type locality) and ceratops (horn-face, Latinized Greek); species name inexpectus refers to the unexpected discovery of an articulated skeleton in the Zhucheng bone-beds.
Zhucheng Dinosaur Museum (ZCDM) V0015, a partial, articulated skeleton including partial maxillae, partial right quadratojugal, jugal, and quadrate, partial left ectopterygoid and pterygoid, nearly complete left and right mandibles, anterior 14 presacral vertebrae and associated ribs, and some additional fragments.
Type locality and horizon
Kugou, Zhucheng County, Shandong Province, China. Upper Cretaceous Wangshi Group
A leptoceratopid with the following autapomorphies: maxilla with a posteroventrally oriented edentulous posterior process, mandible extremely deep (mid-length height about one-third of mandibular length), mandible very thin transversely (ratio of ventral margin width to mandibular length about 0.03), medial surface of mandible with two large fossae separated by thick curved ridge along dentary-splenial contact, predentary sub-vertically oriented (posterior edge forms angle of about 75 degrees with tooth row in lateral view), anterior end of dentary deeper than coronoid region, anterior portion of Meckelian groove floored by both dentary and splenial and much wider than posterior portion, surangular with additional fossa immediately anterior to glenoid fossa, surangular with sharp anteroventral process inserting into dentary in lateral view, articular with semilunate fossa immediately posterior to glenoid fossa, dorsal edge of splenial step-wise in medial view, and middle cervical ribs bifurcated due to presence of prominent accessory dorsal process (condition poorly known in other ceratopians).