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Pterosaur breathing



From: Ben Creisler
bcreisler@gmail.com

A recent paper not yet mentioned:


Nicholas R. Geist, Willem J. Hillenius, Eberhard Frey, Terry D. Jones
& Ross A. Elgin (2013)
Breathing in a box: Constraints on lung ventilation in giant pterosaurs.
The Anatomical Record (advance online publication)
DOI: 10.1002/ar.22839
http://onlinelibrary.wiley.com/doi/10.1002/ar.22839/abstract



Pterosaurs were the first vertebrates to achieve active flight, with
some derived forms reaching enormous size. Accumulating fossil
evidence confirms earlier indications that selection for large size in
these flying forms resulted in a light, yet strong skeleton
characterized by fusion of many bones of the trunk. However, this
process also added mechanical constraints on the mobility of the
thorax of large pterosaurs that likely limited the options available
for lung ventilation. We present an alternative hypothesis to recent
suggestions of an avian-like mechanism of costosternal pumping as the
primary means of aspiration. An analysis of the joints among the
vertebrae, ribs, sternum, and pectoral girdle of large pterosaurs
indicates limited mobility of the ribcage and sternum. Comparisons
with modes of lung ventilation in extant amniotes suggests that the
stiffened thorax, coupled with mobile gastralia and prepubic bones,
may be most consistent with an extracostal mechanism for lung
ventilation in large pterodactyloids, perhaps similar to a
crocodile-like visceral displacement system.