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FW: The ground-nowhere hypothesis on the origin of bird flight (joke)
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Makes sense Augusto. Don't really know myself. I have seen crows
dive on and hit squirrels from trees. They do not hit them that=20
hard. These animals are the size of juvenile Archies. A full
grown raven-sized Archie could probably do a lot better. The=20
sickle claw more powerfully developed in the adult.
David thinks this is impossible. I do not know why he thinks that.
It should be an open possibility. Animals can be very resourcefull.
> Date: Tue=2C 13 Oct 2009 12:41:18 -0300
> Subject: Re: FW: The ground-nowhere hypothesis on the origin of bird flig=
> From: firstname.lastname@example.org
> To: email@example.com
> The trouble about protobirds scaling trees to jump into prey is that=2C
> as I was told by Tim Williams past year when I believed in the
> trees-down hypothesis=2C there is no hard proof of arboreality in
> theropods. Also=2C the mostly parasagittal way of movement of their
> limbs=2C and scarce gripping adaptations=2C suggest they would be too
> clumsy on trees. Feduccia (1993) made me believe the unguals indicated
> arboreality in protoavians=2C but new studies indicate the unguals of
> basal avialans mostly resemble ground birds.
> I once though perhaps the clumsiness of small theropods in trees may
> have required wings and flapping=2C for the airfoils may have helped
> with balance in a tree biped. Gliding or some descending flapping
> flight would have helped the proavian to easily descend (given the
> lack of reversable ankles)=2C and wings may have helped bipedal climbing
> of trees via WAIR (wing-assisted inclined running)=2C which is used by
> some birds. However=2C the trouble with that was that=2C according to
> Evelyn Sobielski=2C you need poweful wings to climb this way=2C like thos=
> in chicken and ducks=2C so perhaps this would be out of reach for
> Archaeopteryx. I suppose less force may be necessary than when flying=2C
> but truly do not know. Even more=2C since the unguals are important for
> climbing=2C I suppose the more curved claws of Archaeopteryx than Gallus
> may require less wing flapping assistance.
> Augusto Haro
> 2009/10/13 dale mcinnes :
>>> Date: Tue=2C 13 Oct 2009 00:17:22 +0200
>>> From: firstname.lastname@example.org
>>> To: email@example.com
>>> Subject: Re: FW: The ground-nowhere hypothesis on the origin of bird fl=
>>>> Any proavis as you would point out would have a fraction of that=3D20
>>>> range but doesn't make it any less viable. Predators like to stick
>>>> around where the prey collects particularly if their range is
>>>> restricted. W=3D aterhole anyone?? --dale (not a joke)
>>> Well=2C if you drag Archie into it=2C both the anatomy and the size of =
>>> animal (or anything like it) make this scenario completely impossible a=
>>> far as I can see. Do you postulate that the evolution of flight happene=
>>> in much larger animals?
>> Why not? Theropods reached a good size during the Early Jurassic.
>> A raven-sized animal could have the mass and with it the speed to
>> hit small prey hard. Or am I missing something here?
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