Philydrosaurus is an extinct genus of which existed in China during the Early Cretaceous. The type species P. proseilus was named in 2005. 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 bone and
postfrontal bone 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 lower temporal fenestra links the genus with more advanced forms.
Paleobiology
A skeleton of
Philydrosaurus has been found with associated post-hatchling stage juveniles, suggesting that they engaged in post-hatching
parental care.
Phylogeny
Phylogeny from the analysis of Dong and colleagues (2020):
