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Protoceratops specimens from Udyn Sayr, Mongolia

From: Ben Creisler

A new paper not yet mentioned on the DML:

Naoto Handa, Mahito Watabe and Khishigjav Tsogtbaatar (2012)
New Specimens of Protoceratops (Dinosauria: Neoceratopsia) from the
Upper Cretaceous in Udyn Sayr, Southern Gobi Area, Mongolia.
Paleontological Research 16(3):179-198

Four skull specimens (MPC-D 100/537,100/538,100/539 and100/540) of
Protoceratopsidae from the Upper Cretaceous in Udyn Sayr, Mongolia are
described, and their ontogenetic stage and expression of sexual
dimorphism are estimated. These specimens are identified as
Protoceratops andrewsi (MPC-D 100/537, 100/539), P. cf. andrewsi
(MPC-D 100/538), and Protoceratops sp. (MPC-D 100/540), respectively.
MPC-D 100/537 and 100/539 are attributed to subadult “female” and
MPC-D 100/538 to subadult “male”. MPC-D 100/540 is adult with unknown

Based on the frill morphologies, the Udyn Sayr specimens are
classified into three types: type 1 (MPC-D 100/539), well developed
ridge on the lateral surface of the squamosal; posteriorly projected
posterior margin of the squamosal; type 2 (MPC-D 100/537), posteriorly
rounded posterior margin of the squamosal; developed ridge on the
posterior margin of the parietal; and type 3 (MPC-D 100/540), large
size; posteriorly curved posterior margin of the squamosal; the rugose
surface texture on the dorsal side of parietal. MPC-D 100/538 could
not be categorized because the specimen's frill is not preserved.
These frill morphologies differ from those of Protoceratops from the
Djadokhta Formation in the adjacent dinosaur locality Tugrikin Shire.
The morphological differences among the Udyn Sayr specimens may
indicate intraspecific variation of Protoceratops.