[N] 2006 Evolution of the respiratoryapparatus and breathing mechanisms in Pterosauria
Claessens, L. (2006) Evolution of the respiratoryapparatus and breathing mechanisms in Pterosauria. JVP 26(3) Abstracts pp.50
An analysis of the postcranial anatomy of basal and derived pterosaurs, including computed tomography (CT) of three-dimensionally preserved remains of the pterodactyloid
Anhanguera santanae, has identified numerous skeletopulmonary specializations consistent with a model for flow-through ventilation of the lungs, suggesting the capacity for highly efficient gas exchange. Pneumatic postcranial bones in pterosaurs imply the existence of a highly-heterogeneous pulmonary system, with both exchange and nonexchange (i.e., air sacs) regions, similar to that known in extant birds and inferred in saurischian dinosaurs.
The absence of intermediate ribs in pterosaurs, including basal forms such as Eudimorphodon and derived pterodactyloids such as Pteranodon, indicates a decrease in
the degrees of freedom of movement of the thorax relative to the basal diapsid condition. The structure of the broad sternal ribs, which articulated with relatively immobile vertebral ribs proximally and a large sternal plate ventrally, indicates that the largest volumetric changes during lung ventilation occurred in the posteroventral thoracoabdominal region.
Posteroventral volumetric changes are further enhanced by a mobile neomorphic prepubis that articulated with an elongate anteroventral condyle on the puboischiadic plate. CT evidence for the presence of pulmonary air sacs in pterosaurs, combined with estimates of the likely range of expansion and contraction of the posteroventral trunk region, supports a skeletal kinematic model for ventilating a flow-through style pulmonary system, specifically adapted for active flapping flight. Pterodactyloid pterosaurs exhibit evidence of further specialization of the respiratory apparatus, including increased fusion within the thoracic skeleton and enhanced postcranial pneumaticity. Such pulmonary specializations likely played a central role in the evolution and diversification of pterosaurs.
An analysis of the postcranial anatomy of basal and derived pterosaurs, including computed tomography (CT) of three-dimensionally preserved remains of the pterodactyloid
Anhanguera santanae, has identified numerous skeletopulmonary specializations consistent with a model for flow-through ventilation of the lungs, suggesting the capacity for highly efficient gas exchange. Pneumatic postcranial bones in pterosaurs imply the existence of a highly-heterogeneous pulmonary system, with both exchange and nonexchange (i.e., air sacs) regions, similar to that known in extant birds and inferred in saurischian dinosaurs.
The absence of intermediate ribs in pterosaurs, including basal forms such as Eudimorphodon and derived pterodactyloids such as Pteranodon, indicates a decrease in
the degrees of freedom of movement of the thorax relative to the basal diapsid condition. The structure of the broad sternal ribs, which articulated with relatively immobile vertebral ribs proximally and a large sternal plate ventrally, indicates that the largest volumetric changes during lung ventilation occurred in the posteroventral thoracoabdominal region.
Posteroventral volumetric changes are further enhanced by a mobile neomorphic prepubis that articulated with an elongate anteroventral condyle on the puboischiadic plate. CT evidence for the presence of pulmonary air sacs in pterosaurs, combined with estimates of the likely range of expansion and contraction of the posteroventral trunk region, supports a skeletal kinematic model for ventilating a flow-through style pulmonary system, specifically adapted for active flapping flight. Pterodactyloid pterosaurs exhibit evidence of further specialization of the respiratory apparatus, including increased fusion within the thoracic skeleton and enhanced postcranial pneumaticity. Such pulmonary specializations likely played a central role in the evolution and diversification of pterosaurs.