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Re: Archaeopteryx and Flight and back again
>> On Tue, 20 Dec 1994, Miles Constable at Edmn wrote:
>> In point of birds 'hopping' as opposed to 'running' (sorry, I already
>> deleted this text), using this modern behavior to suggest that hopping
>> was the preferred mode of transport in the ancestral form seems somewhat
>> presumptuous. I certainly have never seen anything that suggests
>> Archaeopteryx was a hopper (of course, I have seen nothing to the
>> contrary either). The fact that running starts in birds are rare does not
>> discount running as an evolutionary starting point for flight.
As to hopping vs. running: without checking the matter I think it is most
likely that birds that progress on the ground mostly by hopping are either
arboreal species or descendants of arboreal species, used to changing perch
with both feet together. I cannot think of a shorebird or gallinaceous
bird, say, that normally progresses by hopping when on the ground. The
switchover, mind you, is probably not a major one; for example, the Savannah
Sparrow is a hopper, while the Ipswich Sparrow, a close relative usually
treated as only subspecifically different, is apparently a walker.
>I can't get past the idea that from running, leaping/gliding would be an
>energy loss - at least for motion. Running animals tend to stay on the ground
>so that their legs can pump energy into their motion.
It would certainly ad drag and promote lift - making it rather like running
underwater. If the ancestor of Archaeopteryx was indeed terrestrial, I
cannot belive that wing feathers evolved for this purpose: display, or
gliding from promontories, seem much more likely functions.
Ronald I. Orenstein Phone: (905) 820-7886 (home)
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