Re: Dinosaurs burrowed to keep warm

[Tim Williams <twilliams_alpha@hotmail.com>]

Dann Pigdon wrote:

> I haven't read the paper itself, but apparently the robust forelimbs and 
> structure of the jaw may be adaptations for some sort of digging activity.

There's adaptations in the pelvic region too.  As digging adaptations in 
_Oryctodromeus_, the authors mention a wide, fused premaxillae (to loosen or 
move dirt); robust scapula with a prominent acromion process and scapular 
spine (for muscle attachments); and a strengthened 'fulcrum' in the pelvic 
region (including seven sacrals, and expanded proximal caudals).

Several of these features are also seen in _Zephyrosaurus_ and _Orodromeus_, 
and (not surprisingly) the phylogenetic analysis recovers these two and 
_Oryctodromeus_ as a clade.  This clade might have been specialized for 
digging, say the authors.  The clade comes out near the base of the 
Euornithopoda, above an _Agilisaurus_-_Yandusaurus_-Othnielia_ clade, and 
below other "hypsilophodont-grade" ornithopods.

There's no mention of _Drinker_.  I had a vague recollection that Bakker had 
mentioned that _Drinker_ had been found in burrows, but I don't know if this 
was actually published (at least scientifically).

> I wonder whether the tails of these species were less stiffened than the 
> 'average' hypsilophodontid?

No mention of that.  In fact, the base of the tail is reinforced.

Cheers

Tim

_________________________________________________________________
It?s tax season, make sure to follow these few simple tips 
http://articles.moneycentral.msn.com/Taxes/PreparationTips/PreparationTips.aspx?icid=HMMartagline