Re: pterosaur femora sprawl

[John Conway <john.a.conway@gmail.com>]

David Peters wrote:

 > Until I see an example of the kinematics of quadrupedal launching
> from  a horizontal surface, I can't envision it. Not when pterosaur ancestors
> and the first pterosaurs were incapable of touching the ground with
> their forelimbs (while balancing glenoids over toes) -- and they had big
> thighs with a pelvis 1/3 the torso length.

Which first pterosaurs? No pterosaurs (and I mean _none_) had a 
shoulder-knuckle length less then their hip-ankle length.

> Certainly Anhanguera had a different launch mechanism, with the
> largest forelimbs and smallest hind limbs and feet in pterosaurland.

No--/Anhanguera/'s forelimb to hindlimb ratio is on the high side (5.1), 
but no where near /Nyctosaurus/ (6.6, the champ) or /Rhamphorhynchus/ 
(6.2-6.4). /Campylognathioides/ is higher at 5 to 5.6. It's similar to 
/Pteranodon/(4.9). /Eudimorphodon/, /Raeticodactylus/, and 
/Pterorynchus/ have a ratio only slightly lower at ~4.5.

Those ratios are for the total wing, if you only include the "walking 
wing" (i.e., shoulder to knuckle), Anhanguera comes out even closer to 
the mean.

Upshot: /Anhanguera/ is well within the range of normal pterosaur 
proportions (both basal and derived) on the forelimb/hindlimb ratio. 
Lots pterosaurs had piddly legs.

> > we know they walked quadrupedally, 
>
> The beachcombing taxa, yes. No prints yet for the soarers, skimmers,
> insect-eaters, basal forms.

Which taxa do you think were soarers and skimmers? Because /Pteranodon/, 
/Nyctosaurus/, anhanguarids (soarers), /Jeholopterus/ 
(insect-eater/basal) /Raeticodactylus/ and /Eudimorphodon/ (basal), have 
comparatively small legs. Odd adaptation for bipedalism.

Cheers,
John

--
Palaeontography: http://palaeo.jconway.co.uk