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Re: the maniraptoran wrist



----- Original Message -----
From: <GSP1954@aol.com>
Sent: Saturday, September 14, 2002 5:02 AM

> As I detail in Dinosaurs of the Air, the avepectoran wrist and folding arm
> evolved in order to fold wings

The best explanation I've read so far.
(The idea that endotherms could be sit-&-wait predators is hard to believe.
In addition, derived dromaeosaurs look like bad long-distance runners with
their relatively short distal leg segments, but still like very good
sprinters.)

> among fliers,

Now why is that? :-)
(If I had wings bigger than those of *Caudipteryx*, for whatever reason, and
an ornithomimosaur's wrists, I would be incapable of running or even walking
into scrub, I think, pretty regardless of my size. With someone behind me
that might exert some selectionary pressure.)

But then maybe the whole affair evolved a lot earlier, at a time when most
people think feathered wings hadn't yet evolved anywhere.

Daniel J. Chure: The wrist of *Allosaurus* (Saurischia: Theropoda), with
observations on the carpus in theropods, 283 -- 300 in Jacques Gauthier &
Lawrence F. Gall (eds): New Perspectives on the Origin and Early Evolution
of Birds: Proceedings of the International Symposium in Honor of John H.
Ostrom, Yale Peabody Museum 2001

The semilunate carpal of this specimen is intriguing. It's nowhere near as
big as in any dromaeo- or oviraptorosaur, and the wrist as preserved (I was
pretty surprised when I first saw it...) is surely disarticulated, but how
far...?

On the other hand, this could be considered evidence for another hypothesis
that's put up in DA, namely that the basalmost allosauroids were just as
small as many basal coelurosaurs, and that wings have an even longer history
that extends outside Coelurosauria. If Daohugou is not Jurassic, then I
suggest someone with a few millions to spare should have a look at Karatau.
It can't be that *Sordes* and *Batrachognathus* are the only amniotes from
there. :-)