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Re: Caudipteryx suffered from osteoarthritis



On Fri, Jan 6, 2012 at 11:43 AM, Mike Taylor <mike@indexdata.com> wrote:
snip
> And yet no-one doubts that penguins, which lack feathers and flight,
> are birds.  Why?  Because they're descended from incontrovertible
> birds.
snip

Not so sure about that (besides which they have feathers (not flight
feathers, but at the same time obviously not hair or scales) and
they're not the only non-flying birds, infact when they were first
sighted by the portugese(?) they apparently thought they were some
type of c.f. auk, iow instantly recognized as a bird)).
Maybe we recognize them as birds because of an accident of
evolutionary history. IF there was a tremendous radiation of penguins,
so they were more diverse and maybe more marine, and an extinction of
many other birds, so we only had, say, passerines, would people
recognize them as the same type of creature? All 'lizards' are
lizards, they're distinct from 'turtles', and they both widely
considered reptiles. Maybe in the sitation I sketched above we'd
recognize that pengi and passeri are 'birds', but quite different
types. Or imagine if the only feathered creatures were penguins and a
few different deinonychus-type creatures, we might be tempted to say
that they're different creatures entirely.

Its the same problem with birds and dinosaurs, what we have is a very
specialized, highly modified group of dinosaurs that survived the KT
extinction, and then radiated out tremendously to become even more
different. We see one end member of a spectrum today.



-- 
Robert J. Schenck
Kingsborough Community College
Physical Sciences Department
S332 ph# 718-368-5792
Follow Me on Twitter: @Schenck
KCC Class Schedule on Google Calendar: http://tinyurl.com/mqwlcy