Basic avian pulmonary design and flow-through ventilation in non-avian theropod dinosaurs

@article{OConnor2005BasicAP,
  title={Basic avian pulmonary design and flow-through ventilation in non-avian theropod dinosaurs},
  author={Patrick M. O’Connor and Leon P. A. M. Claessens},
  journal={Nature},
  year={2005},
  volume={436},
  pages={253-256}
}
Birds are unique among living vertebrates in possessing pneumaticity of the postcranial skeleton, with invasion of bone by the pulmonary air-sac system. The avian respiratory system includes high-compliance air sacs that ventilate a dorsally fixed, non-expanding parabronchial lung. Caudally positioned abdominal and thoracic air sacs are critical components of the avian aspiration pump, facilitating flow-through ventilation of the lung and near-constant airflow during both inspiration and… 
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181 Citations

Vertebral morphometrics and lung structure in non-avian dinosaurs
TLDR
Although fully avian lungs were a rather late innovation, it is quantitatively show that non-avian dinosaurs and basal dinosauriforms possessed bird-like costovertebral joints and a furrowed thoracic ceiling, which could have permitted high levels of aerobic and metabolic activity in dinosaurs, even in the hypoxic conditions of the Mesozoic, contributing to their successful radiation.
Evidence for Avian Intrathoracic Air Sacs in a New Predatory Dinosaur from Argentina
TLDR
A new predatory dinosaur from Upper Cretaceous rocks in Argentina is described that exhibits extreme pneumatization of skeletal bone, including pneumatic hollowing of the furcula and ilium, and several pneumatized gastralia are described, which suggest that diverticulae of the air sac system were present in surface tissues of the thorax.
Cardio‐pulmonary anatomy in theropod dinosaurs: Implications from extant archosaurs
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The likely absence of bird‐like pulmonary function in theropods is inconsistent with suggestions of cardiovascular anatomy more sophisticated than that of modern crocodilians.
Postcranial Pneumaticity in Dinosaurs and the Origin of the Avian Lung
TLDR
The Air Space Proportion (ASP) is proposed as a measure of proportional volume of air in pneumatic bones, and indicates that increases in the number of cervical vertebrae, their proportional lengths, and their internal complexity occurred in parallel in most of these lineages.
Evolution of the Dinosauriform Respiratory Apparatus: New Evidence from the Postcranial Axial Skeleton
TLDR
Data from this study suggest a progression from a dorsally rigid, heterogeneously partitioned, multichambered lung in basal dinosauriform archosaurs towards the small entirely rigid avian‐style lung that was likely present in saurischian dinosaurs, consistent with a constant volume cavum pulmonale, thin walled parabronchi, and distinct air sacs.
Avian-like breathing mechanics in maniraptoran dinosaurs
TLDR
This study presents a mechanism whereby uncinate processes, in conjunction with lateral and ventral movements of the sternum and gastral basket, affected avian-like breathing mechanics in extinct non-avian maniraptoran dinosaurs.
Evolution of the Respiratory System in Nonavian Theropods: Evidence From Rib and Vertebral Morphology
TLDR
Comparing the thoracic rib and vertebral anatomy of Sinraptor, Allosaurus, Tyrannosaurus, and Deinonychus provides new evidence supporting the hypothesis of flow‐through ventilation in nonavian theropods, and concludes that an avian‐style pulmonary system was likely a universal theropod trait.
Evidence for bird-like air sacs in saurischian dinosaurs.
  • M. Wedel
  • Environmental Science, Geography
    Journal of experimental zoology. Part A, Ecological genetics and physiology
  • 2009
TLDR
Several lines of evidence suggest that air sac-driven lung ventilation was primitive for Saurischia, and anatomical and evolutionary patterns of pneumatization in nonavian saurischian dinosaurs are diagnostic for specificAir sacs, including the cervical, clavicular, and abdominal air sacs.
Pulmonary anatomy in the Nile crocodile and the evolution of unidirectional airflow in Archosauria
TLDR
The data indicate that the aspects of the crocodilian bronchial tree that maintain the aerodynamic valves and thus generate unidirectional airflow, are ancestral for Archosauria.
On the origin of avian air sacs
TLDR
Non-respiratory functions of the lung are considered along with data on the respiratory capacities and gas exchange abilities of birds and crocodilians to infer the evolutionary history of the respiratory systems of dinosaurs, including birds.
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