[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: pterosaur femora sprawl

----- Original Message ----
> From: John Conway <john.a.conway@gmail.com>

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

True. But no pterosaurs walked, bipedally or quadrupedally, with a horizontal 
backbone. Elevate the spine at the shoulders and voila. MPUM 6009 is still 
derived in many regards, so it is the most basal _known_ pterosaur.
> > 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.

True. I had Arthurdactylus in my mind's eye when I wrote Anhanguera. And you 
are so right about certain Nyctosaurus, Rhamphorhynchus and Campylognathoides. 
In any case the point is relative mass or bulk -- not length -- although length 
is more readily measureable and certainly, as you point out, a factor. The 
pelvis, hindlimb and feet of ornithocheirids are so small they are dwarfed, in 
comparison, by the bulk of the wings, despite their length. 
> >> 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.

All pterosaurs except "azhdarchids," ctenochasmatids, dorygnathids (that's one 
clade) and cycnorhamphids + ornithocheirids (a second clade). 

re: Odd adaptation for bipedalism: 
Don't forget the albatross and the hummingbird (comparatively small legs). 
Case closed?  :  )

Best to you, John.  David

> Cheers,
> John
> --
> Palaeontography: http://palaeo.jconway.co.uk