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Mosaiceratops, new basal neoceratopsian from Upper Cretaceous of China (free pdf)



Ben Creisler
bcreisler@gmail.com


A new paper in open access:


Wenjie Zheng, Xingsheng Jin & Xing Xu (2015)
A psittacosaurid-like basal neoceratopsian from the Upper Cretaceous
of central China and its implications for basal ceratopsian evolution.
Scientific Reports 5, Article number: 14190
doi:10.1038/srep14190
http://www.nature.com/articles/srep14190


Psittacosauridae (parrot-beaked dinosaurs) represents the first major
radiation of ceratopsians (horned dinosaurs). However, psittacosaurids
are divergent from the general morphology found in other ceratopsians,
and this has resulted in their uncertain systematic position among
ceratopsians. Here we describe a new basal neoceratopsian dinosaur,
Mosaiceratops azumai gen. et sp. nov. based on a partial
semi-articulated skeleton recovered from the Upper Cretaceous Xiaguan
Formation of Neixiang County, Henan Province, China. Although our
phylogenetic analysis supports this taxon as the most basal
neoceratopsian, Mosaiceratops exhibits many features previously
considered unique to the Psittacosauridae among the basal Ceratopsia.
These include a relatively highly positioned external naris, a
proportionally large premaxilla, the nasal extending ventral to the
external naris, slender postorbital and temporal bars, a large notch
between the basal tubera, and the edentulous premaxilla. Thus, the
discovery of Mosaiceratops reduces the morphological disparity between
the Psittacosauridae and other basal ceratopsians. Character
optimization suggests that basal neoceratopsians have re-evolved
premaxillary teeth; a major reversal previously unknown in any
dinosaur clade. The new specimen also highlights the mosaic nature of
evolution among early ceratopsians and supports the phylogenetic
hypothesis that the Psittacosauridae is a relatively derived clade,
rather than the most basal group of the Ceratopsia.