Re: Hongshanosaurus houi, new psittacosaur

["Mickey Mortimer" <Mickey_Mortimer111@msn.com>]

Tim Williams wrote-

> But I agree that, aside from heterodontosaurids (if
> indeed they are marginocephalians) and _Chaoyangsaurus_, the
> pre-Late-Jurassic marginocephalian fossil record is so far non-existent.

Chaoyangsaurus youngi is Berriasian, according to Swisher et al. (2002).
This makes it equal in age to the pachycephalosaur Stenopelix valdensis and
at least some Psittacosaurus remains (eg. P. sibiricus).
There's also "Xuanhuasaurus niei", from the Late(?) Jurassic Houcheng
Formation of Hebei, China.  At least that's what I assume Makovicky's (2002)
new unnamed chaoyangsaur is (Zhao et al., in prep.).
The supposedly Late Jurassic "Luanpingosaurus jingshanensis" was thought to
be a junior synonym of Psittacosaurus by Wang et al. (2000).
And we all remember Chatterjee's (1998) supposed pachycephalosaurid domes
from the Maleri Formation (Early Carnian).  Goodwin seems to support the
identification morphologically at least, but Chatterjee's record in this
area isn't the best.

Mickey Mortimer