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Re: Ostrom Symposium - Part 4



-----Original Message-----
From: Ronald Orenstein <ornstn@home.com>
To: dinosaur@usc.edu <dinosaur@usc.edu>
Date: Wednesday, March 03, 1999 08:04 PM
Subject: Ostrom Symposium - Part 4


>I've been away in Washington for a few days (and I'm off to Florida in a
>week) so these reports have been getting (and will continue to be)
>intermittent.  Never-the-dagboned-less, as Pogo used to say:
>
>On to day two.  The first session in the morning dealt with the contentious
>subject of feathers.  Alan Brush gave an outline of feather evolution.  He
>suggested that feather variety has been great since the earliest appearance
>of feathers, so that they must have evolved their structure, complexity,
>and a great deal of variety very rapidly.

True if the first feathers we have are close to the first to have existed.
Alan presumably sees Ax as pretty well the first bird.


>
>Zhonghe Zhou provided the only paper by a Chinese scientist.  Zhou examined
>Confuciusornis, especially with respect to its flying ability.  The
>coracoid in this bird is strutlike, and shows a condition somewhat more
>derived than in Archaeopteryx, but it is stuill short and broad, lacking
>the triossial canal that in modern birds allows the tendon of the
>supracoracoideus muscle can act as an elevator of the wing.  You might
>think that this would mean that Confuciusornis could not take off or fly.
>You might be right about takeoff,

If we are right about Archae living on shallow islands in a lagoon with just
the occasional low bush, it would be odd if it couldn't take off from the
ground.  And of course bats don't have the full triossial yet many can take
off from the ground.  Conf. was an enant (or close) and they were different
in a number of ways from uncinated birds.  Perhaps we should be cautious -
remember the bumblebee?



>but, strangely enough, a pigeon with the
>tendon of the supracoracoideus severed can actually fly (using the deltoids
>as wing elevators, as was explained in a later presentation), though it
>cannot take off.  And if a pigeon could do that, so could be early birds
>with their less developed coracoids.  To me, this suggests that
>Confuciusornis (and Archaeopteryx) must have had to gain height to fly
>(Confuciusornis has long, slender wings which do not seem designed for
>ground starts - similarly(?), I have observed myself that long and
>narrow-winged bats of the genus Molossus have to gain considerable height
>to take off, and if released on a tree trunk will hitch themselves up
>thirty feet or so before launching into the air).

Nightjaws/poorwills/nighthawks?


[The relative toe phallanx lengths/arborial-terrestrial stuff was v
interesting...]
>Thus Coelophysis actually comes out rather like
>Archaeopteryx.
[...sometimes very interesting!]


>The next paper was a substitution, given by a graduate student whose name
>escapes me.
[sounds like my mate Alan Gishlick]

> He talked about the use of the forelimbs in maniraptoran
>dinosaurs, including early birds, and in particular the use of the four
>limbs in prey capture.  I have already alluded to this paper in my posting
>on feathers as fossilized behavior, which I'm glad to see has started a
>little discussion here.  The speaker pointed out that although the second
>digit, if it had feathering equivalent to that in modern birds, would have
>given rise to the remiges along its length, the third digit would have been
>free and could have been used to subdue prey.  He compared be possible
>hunting method of Velociraptor to a cat using its forelimbs to catch prey,
>following up with a killing byte (or in the case of Velociraptor,
>presumably a killing slash with the claw of the hind foot).

(It may not be a coincidence that cats have tree-capable front claws.
Surely climbing predators would be more likely to make use of their hands
for predation.)