[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
Re: Phylogenetic bracket question
As I see it, the phylogenetic bracket basically makes predictions more
than conclusions. On phylogenetic grounds, we would predict skin
impressions for Deinonychus to show some sort of plumage -
dromaeosaurids are ultimately descended from an animal with feathers or
protofeathers or whatever, and at least one dromaeosaurid
(Sinornithosaurus) has them. I would still code Deinonychus with a "?"
for such structures, but would expect them should preserved skin be
Is secondary loss a possibility? Sure - the phylogenetic bracket, in
the absence of other evidence, would reconstruct dolphins with fur and
tyrannosaurids with a complete third digit. But without this other
evidence, secondary loss is a less parsimonious statement.
The question to be asked at this point is, why would any nonavian
coelurosaur *not* have had feathers? Some have argued that large-bodied
coelurosaurs (tyrannosaurids, etc.) might have lost them to shed heat,
but we don't know that they were absent. Why would you *want* to
reconstruct Deinonychus without external dermal fibers?
Larry Dunn wrote:
> Well, I never thought I'd be asking this particular
> question, but, at this point, is it at all
> scientifically plausible to argue that _Deinonychus_
> did not have 'feathers"?
> "Atheism: a non-prophet organization."
> Do You Yahoo!?
> Talk to your friends online with Yahoo! Messenger.
Christopher A. Brochu
Department of Geology
Field Museum of Natural History
Roosevelt Road at Lake Shore Drive
Chicago, IL 60605
voice: 312-665-7633 (NEW)
fax: 312-665-7641 (NEW)