[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
Re: flights of fancy (or "I'm brave, but I'm chicken****")
Some weird stuff about Dromaeosaurs:
--Reversed pubes. Why do they have these? One possibility is that
they evolved among flying animals to offset balance problems caused by
wings and large arms, or that they allowed the chest to become
shorter and more compact (as it tends to in flying animals). They evolved
in herbivores, but to allow for a bigger gut. Dromaeosaurs did not evolve
them for this reason.
--Stiffened tail. Not uncommon among dinosaurs, but closely
resembles that of Archies, and less so, Rhamphorhynchs. It's possible
that this was evolved to serve as a feathered elevator/rudder.
--Those funny bones that lie in rows on the dorsal side of the rib
cage- "ulcinaries" Paul calls them. These might have served to stiffen the
rib cage, against the contraction of powerful arm and shoulder muscles.
Well developed on modern birds, these are absent in Archaeopterygians.
--the folding arms. Are we seriously supposed to buy that folding arms
were more efficient for some running theropods, and coincidentally,
a few million years later, they happen to be useful for birds trying
to keep their flight feathers out of the way and out of harms way? Yeah,
--big breastplate. I'll bet you the furcula is unusually large as
well among the Dromaeosaurs. (George?)
--big arms. Theropods in general, from Tyrannosaurs to Carnotaurs,
have evolved smaller arms. Why the big reversal in Dromaeosaurs?
--There hasn't been any good evidence argued against it. This
doesn't really count, but has anybody shown any reasons why this can't
work? I can understand how some of these might work as arboreal
adaptations, but others... Some of these have plenty of other
interpretations, I admit.
The point is not that Archaeopterygians and Dromaeosaurs share a
lot of features. That only proves that they were related, not how. The
point is a lot of Dromaeosaur features seem to make little sense
outside the context of a flying ancestor.