[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
Re: Mammal - Like - Reptiles ... info needed.
>For that matter, what is the current status of the pelycosaurs? It seems
>to me that I had heard a couple of years ago that they were no longer
>considered a valid group, but I have continued to see them refered to since
Virtually all phylogenetic analyses of Synapsida show "pelycosaurs" to form
a paraphyletic assemblage. We could have defined a monophyletic
Pelycosauria, but it would have been completely redundant with Synapsida.
The word "pelycosaur" is sometimes used as an informal morphological
descriptor, e.g. "Dimetrodon is a pelycosaur-grade synapsid." This implies
a range of morphology, not membership in a taxon. As such, it's no
different than describing Tyrannosaurus as a nonavian dinosaur.
Christopher Brochu, Ph.D.
Postdoctoral Research Scientist
Department of Geology
Field Museum of Natural History
Lake Shore Drive at Roosevelt Road
Chicago, IL 60605 USA