Re: Birds and archosaurs

[cnedin@geology.adelaide.edu.au (Chris Nedin)]

Bill Barbour writes:

>An intern of mine is working on a report for her vertebrate morphology class
>about the origins of the avians. She has come across a number of strange
>theories which I have not heard of. One, is advanced by a paper by Martin
>(and others) in the early 80's stating that the crocodilians gave rise to the
>birds. Does anyone out there know the background of this "theory"?
>Also, there was some work published early this year which suggested that Late
>Cretaceous birds show growh rings within their bones and may have been
>ectothermic, or at least not totally endothermic. Does anyone know what
>became of this idea?
>I'd appreciate any comments.

Re crocodilian affinities:

It was suggested by Walker (1972, 1974) that birds (and hence
_Archaeopteryx_) arose from an almost unknown Middle or Late Triassic
reptile group, the Sphenosuchidae , which also gave rise to the crocodiles.
The theory is based on a single specimen of _Sphenosuchus_. However,
according to Ostrom (1976), in their general configurations, neither the
skull and jaws, nor the scapulo-coracoid of _Sphenosuchus_ is remotely
suggestive of affinities with Archae.

Chris

refs

Ostrom, J. H. (1976) Archaeopteryx and the origin of birds. Biological
Journal of the Linnean society, 8(2): 91-182.

Walker, A. D. (1972) New light on the origins of birds and crocodiles.
Nature, 237: 257-263.

Walker, A. D. (1974) Evolution, organic. In Yearbook of Science and
Technology, D.N. Lapedes (ed). pp. 177-179. McGraw-Hill, New York.