[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
EUPARKERIA & BRAINCASE HOMOLOGIES
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
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"