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Re: Pterosaur morphological evolution
On Jul 7, 2011, at 5:15 AM, Mark Witton wrote:
> On a related note, has anyone ever wondered why
> Raeticodactylus/Caviramus has such a narrow humeral diaphysis? It's
> seriously stick thin. It's still got a large DPC and flight finger,
> though, so I don't know that it necessarily reflects flightless habits.
> Interestingly, its femur is probably more robust than its humerus, a
> feature only otherwise seen in Preondactylus. Looks to me like
> Raeticodactylus/Caviramus is just begging for some a nice biomechanical
> investigation of its limb strength: it would be particularly interesting
> to know if it could quad launch.
I've been wondering that myself, actually - but I have not had a chance to look
at the Raeticodactylus material in detail. It's a weird animal. Perhaps it
was more bipedal than other taxa.
On Jul 8, 2011, at 2:35 AM, Tim Williams wrote:
> _Raeticodactylus_ also has a femoral head that is perpendicular to the
> shaft, as in dinosaurs (this was noted in the original description:
> Stecher, 2008). So maybe it was better at bipedal launching?
Good point. Again, perhaps it was a biped launcher, instead. It is also
possible for a quad launching animal to use a more balanced force output from
the hindlimbs and forelimbs - it doesn't have to be forelimb dominated, but
quadrupedal launching should tend to favor a forelimb-dominated cycle because
it improves multimodal efficiency (i.e. robust forelimbs improve both launching
and flight for a quad locomotor, so the most mechanically efficient mode is
robust forelimbs and gracile hindlimbs). Competing demands could lead to
robust hindlimbs, or perhaps Raeticodactylus was just largely bipedal.
Interesting stuff all around!
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