RE: First New Dino of 2010

[Tim Williams <tijawi@yahoo.com>]

Tom Holtz <tholtz@umd.edu> wrote:


> In the broader systematic implications of this paper, they regard
> Homalocephale as a juvenile of the sympatric Prenocephale, and 
> Wannanosaurus and Goyocephale as juveniles of (almost certainly domed)
> otherwise undiscovered adult taxa. Thus there are at present no
> flat-headed adult pachycephalosaurs. 


I was a little surprised at this, but I should really have seen it coming, in 
light of what was happening to the N. American pacycephalosaur genera.


Interestingly, _Prenocephale_ and _Homalocephale_ were named and described in 
the same paper (Maryanska and Osmolska, 1974).  _Prenocephale_ was named + 
described three pages before _Homalocephale_, so if the two genera are formally 
synonymized, then _Prenocephale_ presumably has priority.


Also, the paper states: "_Yaverlandia bitholus_ and _Micropachycephalosaurus 
hongtuyensis_ are no
longer believed to represent pachycephalosaurids (Sullivan, 2003; Butler and 
Zhao, 2009)."  This is certainly true of _Yaverlandia_ (theropod); but the 
affinities of _Micropachycephalosaurus_ are a little murkier.  Butler and Zhao 
(2009) found _Micropachycephalosaurus_ to be a member of the Cerapoda, but the 
fragmentary material meant its position could not be resolved further.  Thus, 
this genus MIGHT be a pachycephalosaur, as Butler and Zhao (2009) note.  Dong 
(1978) originally reported a thickened skull roof, but this could not be 
located.  The phylogenetic analysis of Zheng et al. (2009) (in the _Tianyulong_ 
paper) found _Micropachycephalosaurus_ to be a basal ceratopsian, but I don't 
know what the statistical support for this position was. 


Cheers

Tim