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Re: pterosaur femora sprawl



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