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Re: Re: Synapsids are NOT reptiles!




On Fri, 15 Dec 1995, Stan Friesen wrote:

> From: Thomas_R_HOLTZ@umail.umd.edu (th81)
>  > Thrinaxodon has never been considered a mammal (except by Van Valen,
>  > who used "Mammalia" as most systemicists now use Synapsida).
>  > It is, however, pretty close to the origin of mammals.
>  > 
> Very close indeed. There is some evidence that it was furry, and
> had vibrissae (facial "whiskers" as in cats and mice).
> 

 Vibrissae leave no mark on bones, not even the hypertrophied spine like 
vibrissae of pinnipeds. So the pits on the snout of Thrinaxodon are not 
evidence for the presence of vibrissae. They may be foramina for nerves 
and blood vessels associated with enlarged lips and facial muscles. 
Also vibrissae are not restricted to the face, they are found on the 
wrists and forearms of rodents and carnivores. Recent research has shown 
that these are important for coordination of the hand while reaching for 
food items.

Adam Yates