EUPARKERIA & BRAINCASE HOMOLOGIES

[darren.naish@port.ac.uk]

First off, a happy new year to everyone. 

Some of you may remember Matt Troutman's recent questions about 
Welman's (1995) paper on the homology of archosaur braincases. Welman 
(1995) contends that, based on braincase characters, _Euparkeria_ is 
closer to birds than are either crocodyliforms or dinosaurs. Needless 
to say, this is highly controversial and runs counter to other 
archosaur phylogenies. 

Welman's paper formed the focus of a talk Dr. David Gower gave at 
SVPCA, Bournemouth, last year. Working together with the 
ornithologist Erich Weber, Gower was able to show that Welman's 
purported cases of homology between _Euparkeria_ and birds were 
incorrect or mistaken, and in fact the data truly supported (1) the 
division of archosaurs into a crocodile branch and a bird branch, (2) 
the nesting of birds within ornithodirans, and (3) the exclusion of 
_Euparkeria_ from the crocodile-bird crown group.

As Gower pointed out, it is curious that Welman's case was largely 
ignored once published. Also, it was never employed as an apparently 
crucial piece of evidence by those who strongly disagree with the 
nesting of birds within Dinosauria. Perhaps this is because braincase 
characters are too complex to be understood by the majority of 
interested parties (I still struggle over braincase anatomy myself 
(despite a slow and thorough reading of Makovicky and Norell (1998), 
the latest contribution on the subject)), or perhaps those who could 
have employed Welman's conclusions to their apparent advantage were 
unaware of his paper.

Gower and Weber's objections have now been published:

GOWER, D.J. and WEBER, E. 1998. The braincase of _Euparkeria_, and 
the evolutionary relationships of birds and crocodiles. _Biological 
Reviews_ 73: 367-411.

Please refer to this work for all the details: includes much 
discussion of braincase anatomy. Incidentally, some other Welman 
ideas may also prove controversial in the future. Welman has 
contended that _Euskelosaurus_ is the most primitive dinosaur, and I 
know he also has some heterodox opinions about the identities of some 
Cretaceous bird or near-bird taxa. Stay tuned!

"We're raptors and don't *you* forget it"

DARREN NAISH
darren.naish@port.ac.uk