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CRETACEOUS 'PRIMATES'



Concerning faunal diversity in the late Maastrichtian, Nick Pharris 
wrote...

> Correct me if I'm wrong (I'm sure somebody would have anyway :-), but hadn't 
> Primates likely already appeared at the time of the K-T extinctions?

Animals that used to be regarded as primitive primates - the 
plesiadapiforms, purgatoriids, apatemyids and others - have been 
excluded from Primates in many recent studies; the 'new' Primates 
encompasses adapiforms, omomyiforms and the lemur-haplorhine 
crown-group. Beard (1983) erected the Primatomorpha to include 
dermopterans, plesiadapiforms, the other early Tertiary groups, and 
primates. Therefore: things in the earliest Cenozoic and (debatably) 
the latest Cretaceous, like _Purgatorius_, would be non-primate 
primatomorphs. True primates don't appear until the late 
Palaeocene (when _Altiatlasius_ from Morocco, probably an omomyiform, 
appears) - and this is in agreement with the distribution of their 
closest relatives - living groups including tarsiers debut in the 
Eocene.

There is considerable doubt attached to the single tooth record for 
_Purgatorius_ from Montana, as apparently the sieve in which the 
specimen was discovered had been used previously for sieving in 
Palaeocene sediments (CHECK THE ARCHIVES!! IT HAS BEEN COVERED 
BEFORE, courtesy Jerry Harris I think). If, however, purgatoriids and 
relatives were present this early, dermopterans may have been around 
too. Beard (1983 and other papers) and McKenna and Bell (1997 - the 
monumental _Classification of Mammals Above the Species Level_) 
regard plesiadapiforms (or some plesiadapiforms) as members of the 
Dermoptera, however, so this group may not have evolved until the 
Palaeocene. 

If this all seems confusing, it is because the experts hold markedly 
different views on early primatomorph evolution. There is also the 
idea - Szalay discussed it in JVP recently in his review of McKenna 
and Bell - that dermopterans and bats should be united as a group 
called the Volitantia. At times I'm glad to work on theropods:)

"Your insight serves you well"

DARREN NAISH 
PALAEOBIOLOGY RESEARCH GROUP
School of Earth, Environmental & Physical Sciences
UNIVERSITY OF PORTSMOUTH
Burnaby Building
Burnaby Road                           email: darren.naish@port.ac.uk
Portsmouth UK                          tel: 01703 446718
P01 3QL                               [COMING SOON: 
http://www.naish-zoology.com]