[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
Re: 11th specimen of Archaeopteryx
On 10/31/2011 12:44 AM, David Marjanovic wrote:
This is nonsense. If you need to hold tree branches for a living (as in:
not falling down when you sleep), there will be natural selections for
adaptations that make this easier and against, say, cursorial
adaptations that make it harder.
So I disagree strongly -- arboreal specializations are NOT expected
in an animal that roosts, but otherwise pursues it's daily (or
nightly) business in cursorial fashion on the ground.
Grasping specializations, however, _are_ expected.
No, they aren't. The claws (and teeth) are sufficient functionally.
Your base assumptions (need to "hold" branches, likelihood of falling,
negative implications of falling, and also shapes of trees) are incorrect.
The idea that a crow-sized animal like Archie could not sleep in a tree
is bogus. Coons curl up in tree crotches like you might curl up on a
couch. Absolutely no holding involved...
There were no doubt some individual trees that were not suitable to
climb and/or roost, likely even whole clades that were not. So what?
The powerstroke is the downstroke, not the upstroke. The upstroke, which gets
the wings out of the way of drag as much as possible before the next
downstroke, is what was (apparently) limited in Archie and *Confuciusornis*.
Yes, of course. But when the upstroke is limited, so is the downstroke,
both geometrically and in terms of available power.
They don't contradict the TR part. Archie's skeleton does,
Nope. See above.
BTW, you mentioned trees taller than 3 m. Precisely such trees appear not to
have existed in Archie's environment, unless all known individuals were blown
in from the presumably forested Bohemian Mass 200 km away and didn't live on
the small islands in the lagoon. -- Of course, this doesn't apply to
*Anchiornis*, *Xiaotingia*, *Microraptor*, or any other of the Chinese beasties.
Yes. I do assume 1) that Archie (and more importantly, Archie's
ancestors not to mention sisters and cousins) was/were not confined to
the exact environs wherein preserved, but had a much wider range.