Re: YAVERLANDIA

["Timothy Williams" <twilliams_alpha@hotmail.com>]

Joe Parish wrote:

> Have you got any further information regarding the identity of Yaverlandia 
> bitholus?
>
> Maryañska (1990) stated that "Hopson (1979) doubted the relationship of Y. 
> bitholus with other pachycephalosaurs because of the structure of its 
> fragmentary endocranial activity. Although these differences in the 
> endocranial cast are significant, it is also true that Y. bitholus shares 
> with other pachycephalosauridae two characters not found in any other 
> ornithischians: the thickening and doming of the skull roof and the 
> textured nature of its dorsal surface" (pp.574-575).

I believe these two characters are also found in _Majungatholus_, an 
abelisaur.  From memory, "thickening and doming of the skull roof" is also 
seen among the Indian abelisaur material.

The possibility of _Yaverlandia_ being an ankylosaur was raised in a popular 
dinosaur book by David Lambert (can't remember which one, but published some 
time in 1990's).  He's also repeated this possibility elsewhere in person:
http://www.cmnh.org/fun/dinosaur-archive/1996May/0307.html

The exact reason (maybe based on one of Steven Hutt's new Isle of Wight 
discoveries) remains elusive.  It's worth remembering though that 
_Yaverlandia_ remains the only known pachycephalosaur from outside North 
America and Asia.  All other non-Asiamerican putative pachycephalosaurs (try 
saying THAT ten times quickly :-) ) have been re-assigned (_Majungatholus_, 
_Taveirosaurus_), although I think the jury's still out on _Stenopelix_ 
(pachy, ceratopsian, or basal marginocephalian?).

As for the domes from the Maleri Formation of India...  This is one of the 
earliest dinosaur-bearing horizons anywhere in the world.  Pachys from the 
Carnian...?  Hmmm.  These I have to see.

> Are there any ankylosaurians with skull roof thickening and texturing?

Almost all of them, I would guess.  Whether it would lead one to be mistaken 
for a pachycephalosaur is another matter.  It would be interesting to look 
into (especially the Wealden ankylosaurs).


Tim



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