Philydrosaurus

Philydrosaurus Temporal range:
Fossil specimen preserving skin impressions, National Museum of Natural Science
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Order:	†Choristodera
Genus:	†Philydrosaurus Gao and Fox, 2005
Species
†P. proseilus Gao and Fox, 2005 (type)

Philydrosaurus is an extinct genus of choristoderan which existed in China during the Early Cretaceous. The type species P. proseilus was named in 2005. Philydrosaurus is closely related to the choristodere Monjurosuchus, and both have been placed in the same family Monjurosuchidae. Philydrosaurus was found from the Jiufotang Formation and is slightly younger than Monjurosuchus, which was found from the Yixian Formation.

Description

Distinct ridges cover the prefrontal and postfrontal bones of the skull, distinguishing Philydrosaurus from related genera. The lower temporal fenestra, usually present as a hole in the back of the skull of choristoderes, is closed by bone in Philydrosaurus. The eye sockets are large and spaced close together, similar to Monjurosuchus and Lazarussuchus. Philydrosaurus is considered more basal than these choristoderes because its eyes are not as closely spaced and face laterally rather than dorsally. The skull is similar in shape to that of Cteniogenys, the most basal choristodere. The shortness of the skull and the laterally facing eye sockets likely represent the ancestral condition for choristoderes, but the closed fenestra links the genus with more advanced forms.