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Breathing in a box: Constraints on lung ventilation in giant pterosaurs
Author(s) -
Geist Nicholas R.,
Hillenius Willem J.,
Frey Eberhard,
Jones Terry D.,
Elgin Ross A.
Publication year - 2014
Publication title -
the anatomical record
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.678
H-Index - 62
eISSN - 1932-8494
pISSN - 1932-8486
DOI - 10.1002/ar.22839
Subject(s) - sternum , rib cage , anatomy , biology , thorax (insect anatomy) , ventilation (architecture) , extant taxon , trunk , lung , evolutionary biology , medicine , ecology , engineering , mechanical engineering
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 Anat Rec, 297:2233–2253, 2014. © 2013 Wiley Periodicals, Inc.