(Fwd) Re: LATE SURVIVING CYNODONT

[Pieter.Depuydt@rug.ac.be]

Dear All,

Here is an answer  that I wouldn't withold from you.
It comes from Martin Jehle, who was subscribed to the dinosaur list for a while,
and who is rather familiar with early mammals.

Pieter Depuydt


------- Forwarded Message Follows -------
From:          "Martin Jehle" <martin.jehle@klinik.uni-regensburg.de>
Organization:  Universitaet Regensburg
To:            Pieter.Depuydt@rug.ac.be
Date:          Mon, 9 Jun 1997 08:16:12 +0200
Subject:       Re: LATE SURVIVING CYNODONT
Priority:      normal


I suppose that if a living Cynodont was found, the 
discussion whether it was already a mammal would still continue after 
its dissection. As far as I know, the jawbone articulation is no 
longer generally regarded as the single criterium for distinguishing 
between  mammal-like reptiles and mammals. The border between the two 
groups is drawn by each author according to his personal preferences. 
Authors have even named clades like Mammaliaformes which express that 
some forms are in a transitional state and cannot yet be classified 
as "true" mammals (Mammalia), but are very closely related to them.

In addition, it cannot be excluded that the final condition of the 
jawbone articulation as we find it in mammals evolved independently 
in several lineages (even if all extant mammals may belong to one of 
those clades).  If Mammalia were defined by the condition of their 
jawbone articulation, all of those independant lineages were mammals 
by definition, but their common ancestor would still be a mammal-like 
reptile.