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Re: propaganda of the majority

>Actually, it was Ostrom who proposed the "insect net" theory, and he has
>never strongly endorsed it.  He just wanted to get yet another idea out
>there for people to consider.

What do you make of this "insect net theory". Do you find it plausible?
Can you suggest any other evolutionary advantage other than insect
capture which would lead to the evolution of flight feathers in a 
cursorial biped?

>[Padian quote deleted]
>These comments miss the main argument of the cursorial hypothesis: the fact
>the birds alone among flying/gliding vertebrates have forelimbs highly
>transformed for flight, but hindlimbs still wholly adapted for terrestrial
>locomotion.  Bats, pterosaurs, flying lizards, flying frogs, flying
>"lemurs", etc., all have wing/patagia on their hindlimbs, whereas birds
>(including Archaeopteryx) have fully erect legs.

I don't find this convincing evidence for a cursorial hypothesis. For one 
thing, bipedalism and occupying the same niches could lead to convergent 
forms in the hindlimbs of birds and late Cretaceous theropods. 

>>With respect to the dinosaurian origin of birds, Feduccia says:
>>"If Archaeopteryx lived in trees, it means that it evolved not from
>>dinosaurs as most paleontologists currently believe, but from some
>>tree-dwelling reptile, since dinosaurs lived on land and not in trees".

>It's good to know that Alan knows the whole of dinosaurian diversity, since
>those of us who work on them still find strange new morphotypes every few
>years :-)

I think Alan's point here is that there are no documented arboreal
characters in theropods in the fossil record (other than possibly those 
of Archaeopteryx if you call it a theropod). Kevin Padian AGREES with 
Alan on this point. Has anyone documented some arboreal theropod
characters recently? What leads you to believe Greg Paul may be right
about small theropods being arboreal?


>Hmmm...You might tell me...Do you...ahem...cling onto any study that
>supports the arboreal hypothesis, even if it is inadequate? :-)

I try not to cling to anything if it's inadequate :-)
(nice touche' though)

>Actually, Phil Currie is working on sme of these ideas.  An important point
>with the last comment - Archie's tail is similary rigid, best seen in the
>newest specimen.  If the rigid tail of dromaeosaurids is reason to reject
>their arboreality, than it should reject it for Archie.

Aren't dromaeosaurids physically larger than Archie? Presumably, the larger
the creature the more difficulty it would have maneuvering in the trees with
a stiff tail. Besides, the rigid tail of dromaeosaurids is not in itself
a reason to reject their arboreality, it's only one factor. In contrast to
Archie, dromaeosaurids lack flight feathers, sharp toeclaws that most 
closely resemble those of modern perching birds(Feduccia), and semi-erect 
posture (unless Martin's reconstruction is flawed). The reason to reject 
dromaeosaur arboreality is the lack of _any_ arboreal characters. 

You may not agree that the evidence points to arboreal Archie. Fair enough. 
The evidence cited to support arboreal Archie is surely not unequivocal.
But if Archie spent so much time running around on the ground, why don't 
the points of his toeclaws look like a roadrunners(i.e. worn). IMHO, His 
neat Jurassic manicure job is consistent with the arboreal theory but 
contradictory to the cursorial theory. 

Paul Sereno has provided a good minimum date for an arboreal lifestyle
in birds. In his paper (Science, around Feb 92?) he suggested that Sinornis
(Chinese bird) was occupying an arboreal habitat no more than 15 million 
years after Archie. I don't recall him advocating an arboreal Archie, but
he presented a very strong case for Sinornis to be arboreal at 135 million 
years ago. 

>By the way, I'm not wholly converted one way or the other to
>cursoriality/arboreality.  Nevertheless, I've had to seek to undo disservice
>done to the cursorial arguments by rigidly-arboreal theorists.  Hope these
>comments are useful, and I appologize for their length.

I consider myself more of a "cursorial basher" than "rigidly-arboreal 
theorist", but I don't think my intellectually honest critique of the
cursorial theory results in a "disservice" to anything. And I for one
thank you for your comments and find them useful. Like many others, 
I'm intrigued by the question of bird origins and enjoy a good debate 
on the subject.

As I've said before, if I had $100 to bet on the bird ancestor, 
I would put $40 on a theropod, $40 on a crocodilian, and $20 on
something else. I envision a tree-dwelling reptile that evolves
powered flight by first gliding from tree-tree or tree-ground
and culminating with all out powered flight. I've never heard
a cursorial-origin-of-flight arguement that I thought could stand
up to even a little scrutiny. I'd like to hear more if you have any.
(P.S. I might be willing to go $50 on a theropod).

It appears to me that arboreality is the common denominator of all
flighted vertebrates, be they reptiles, birds or mammals. If the
theropod-bird lineage is correct, the proto-bird was most likely 
bipedal _before_ it became arboreal. So I don't unconditionally rule
out a cursorial component to the story if you look back far enough,
but by the time you get to Archie, they've already been in the trees
for a while.