The Lung Air Sac System of Birds

Duncker, Hans-Rainer

doi:10.1007/978-3-662-10354-8

Cited by 76 publications

(144 citation statements)

References 41 publications

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“…These modifications facilitate ventilation of abdominal air sacs, while costal action results in a dorsoventral rocking motion of the posterior end of the enlarged sternum, which expands and contracts the air sacs (King 1966;Schmidt-Neilsen 1971;Brackenbury 1987;Fedde 1987). The highly derived avian lung air sac system, which permeates the entire pleuroperitoneal cavity, is dependent on the aforementioned skeletal features (Duncker 1972(Duncker , 1974(Duncker , 1989 and precludes the distinct transverse separation of avian body cavity that is typical of diaphragmbreathing tetrapods.…”

Section: Lung Morphology and Ventilation In Extant Amniotesmentioning

confidence: 99%

“…Since abdominal air sacs are of fundamental importance to the function of the lung in extant birds (Duncker 1971), their likely absence is another indication that an avian-style, flow-through, air sac lung was absent in theropod dinosaurs. Alternately, Scipionyx's axial skeletal features and distinct visceral organization are consistent with the presence of hepatic piston, diaphragm-breathing.…”

Section: Lung Morphology and Ventilation In Early Birds And Dinosaursmentioning

confidence: 99%

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Respiratory and Reproductive Paleophysiology of Dinosaurs and Early Birds

Ruben

Jones²,

Geist³

2003

Physiological and Biochemical Zoology

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In terms of their diversity and longevity, dinosaurs and birds were/are surely among the most successful of terrestrial vertebrates. Unfortunately, interpreting many aspects of the biology of dinosaurs and the earliest of the birds presents formidable challenges because they are known only from fossils. Nevertheless, a variety of attributes of these taxa can be inferred by identification of shared anatomical structures whose presence is causally linked to specialized functions in living reptiles, birds, and mammals. Studies such as these demonstrate that although dinosaurs and early birds were likely to have been homeothermic, the absence of nasal respiratory turbinates in these animals indicates that they were likely to have maintained reptile-like (ectothermic) metabolic rates during periods of rest or routine activity. Nevertheless, given the metabolic capacities of some extant reptiles during periods of elevated activity, early birds were probably capable of powered flight. Similarly, had, for example, theropod dinosaurs possessed aerobic metabolic capacities and habits equivalent to those of some large, modern tropical latitude lizards (e.g., Varanus), they may well have maintained significant home ranges and actively pursued and killed large prey. Additionally, this scenario of active, although ectothermic, theropod dinosaurs seems reinforced by the likely utilization of crocodilian-like, diaphragm breathing in this group. Finally, persistent in vivo burial of their nests and ap-*

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Section: Lung Morphology and Ventilation In Extant Amniotesmentioning

confidence: 99%

Section: Lung Morphology and Ventilation In Early Birds And Dinosaursmentioning

confidence: 99%

Respiratory and Reproductive Paleophysiology of Dinosaurs and Early Birds

Ruben

Jones²,

Geist³

2003

Physiological and Biochemical Zoology

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“…The horizontal septum (hs) underlies the vascularized portion of the lung and the oblique septum (os) surrounds digestive viscera (not depicted), separating them from the air-sacs. St, sternum (modified from Duncker, 1971). 1997). Experimental occlusion of the abdominal air-sacs in domestic fowl decreases lung ventilation, greatly reducing arterial blood oxygen tension (by about 20%) and diminishing endurance during even minimal exercise (factorial aerobic scope 3) (Brackenbury and Amaku, 1990).…”

Section: Introductionmentioning

confidence: 99%

“…Energy must be expended during all stages of ventilation because the flimsy air-sac walls posses no significant number of elastic fibers capable of recoil (Duncker, 1971). While flying at their preferred speeds in a wind tunnel, black-billed magpies (Pica pica) generate peak expiratory pressures of roughly 2 cm H 2 O in their anterior clavicular air-sac and 8 cm H 2 O in posterior thoracic air-sacs, about a 63 increase over those observed at rest (Boggs et al, 1997).…”

Section: Introductionmentioning

confidence: 99%

“…Although ribs and sternum move significantly during ventilation, the avian rib cage maintains a minimum volume below which the thoracic wall cannot collapse. The viscera are separated from the compliant air-sacs in the thoracoabdominal cavity where inelastic oblique and horizontal septa divide the cavity into two subpulmonary cavities and one peritoneal cavity (Duncker, 1971). Paired subpulmonary cavities are bounded dorsally by the horizontal septum (dorsal to which is found the lung), medially and caudally by the oblique septa (which spans from vertebral column to the Zimmer, 1935. sternum and caudal, lateral body wall) and laterally and ventrally by the rib bearing body wall ( Fig.…”

Section: Introductionmentioning

confidence: 99%

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Cardio‐pulmonary anatomy in theropod dinosaurs: Implications from extant archosaurs

Quick

Ruben

2009

Journal of Morphology

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Although crocodilian lung and cardiovascular organs are markedly less specialized than the avian heart and lung air-sac system, all living archosaurs possess four-chambered hearts and heterogeneously vascularized, faveolar lungs. In birds, normal lung function requires extensive, dorsally situated nonvascularized abdominal air-sacs ventilated by an expansive sternum and specially hinged costal ribs. The thin walled and voluminous abdominal air-sacs are supported laterally and caudally to prevent inward (paradoxical) collapse during generation of negative (inhalatory) pressure: the synsacrum, posteriorly directed, laterally open pubes and specialized femoral-thigh complex provide requisite support and largely prevent inhalatory collapse. In comparison, theropod dinosaurs probably lacked similarly enlarged abdominal air-sacs, and skeleto-muscular modifications consistent with their ventilation. In the absence of enlarged, functional abdominal air-sacs, theropods were unlikely to have possessed a specialized bird-like, air-sac lung. The likely absence of bird-like pulmonary function in theropods is inconsistent with suggestions of cardiovascular anatomy more sophisticated than that of modern crocodilians.

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Cagebirds

Hawkins¹,

Pascoe²

2007

Zoo Animal and Wildlife Immobilization and Anesthesia

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The Lung Air Sac System of Birds

Cited by 76 publications

References 41 publications

Respiratory and Reproductive Paleophysiology of Dinosaurs and Early Birds

Respiratory and Reproductive Paleophysiology of Dinosaurs and Early Birds

Cardio‐pulmonary anatomy in theropod dinosaurs: Implications from extant archosaurs

Cagebirds

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