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Pterosaur floating posture



From: Ben Creisler
bcreisler@gmail.com


A new online paper:


David W.E. Hone & Donald M. Henderson (2013)
The posture of floating pterosaurs: Ecological implications for
inhabiting marine and freshwater habitats.
Palaeogeography, Palaeoclimatology, Palaeoecology (advance online publication)
doi: http://dx.doi.org/10.1016/j.palaeo.2013.11.022
http://www.sciencedirect.com/science/article/pii/S0031018213005257


The highly pneumatic skeleton of the extinct flying pterosaurs
suggests that they would float high up on open water, but in a posture
rather different to that of birds. However, the exact posture of the
body and head remains unknown and would be critical for an ocean going
pterosaur forced onto the waters’ surface or animals that alighted to
feed. Using computational methods with recent models and body mass
estimates for four pterosaur genera – Dimorphodon, Rhamphorhynchus,
Pteranodon and Dsungaripterus we show that the floating posture of
pterodactyloid pterosaurs led to the head, neck and body being
horizontal with the ventral 1/4 to 1/3 being immersed, and the
external nares being almost at, or potentially partially below, the
waterline that could have left them vulnerable to drowning. The
floatation methods were verified using a model of a Canada goose
(Branta canadensis) that is able to successfully replicate the
expected orientation and depth of immersion of the bird. While there
is convincing evidence for a number of pterosaurs foraging in marine
and freshwater environments, these results suggest many did not
regularly rest on the surface of the water and if immersed would need
to take off again rapidly. The high numbers of fossils of juvenile
pterosaurs compared to the terrestrial Mesozoic dinosaurs suggests
that this may be linked to their poor ability in water.