Re: LATE SURVIVING CYNODONTS

[Gautam Majumdar <gautam@majumdar.demon.co.uk>]

Darren Naish  wrote
>
>People continue to overlook _Chronoperates_, a non-mammalian cynodont from the
>Palaeocene. This taxon (known from a posterior mandible) was deemed distinct
>enough for its own family. If the allocation is correct (I recall from the 
>paper
>that the case was very good as no other identity agreed with the characters),
>_Chronoperates_ shows that tritylodontids were not the last non-mammalian
>cynodonts, and that there were elusive little ones running around throughout
>the Cretaceous and surviving across the KT boundary.
>
>_Chronoperates_ was described in _Nature_ in 1992 or thereabouts - I'm afraid
>I don't have the reference to hand. To denote its remarkably unexpected
>occurrence (it's a Cainozoic 'living fossil'), the name given to it means 'Time
>wanderer'. It's possible that I'm out of date on this matter and maybe opinions
>on this fossil have changed. Please let me know if so. 

Chronoperates Reference :

Fox R C, Youzwyshyn G P, Krause D W, Post-Jurassic mammal-like reptile 
from Palaeocene, Nature 1992; 358: 233-35  

This claim has been refuted on anatomical grounds (Sues HD, No 
Palaeocene 'mammal-like reptile', Nature 1992; 359: 278.).  There were no 
clear similarity  with non-mammalian cynodont for which the claim was made 
but the similarity with Symmetrodont mammals was very close.  Several 
features, including the absence of cingula, which were presented as  
evidence for therapsid (non-mammalian cynodont) origin were also found in 
some earliest mammals like Sinoconodon.

Gautam Majumdar                 gautam@majumdar.demon.co.uk