Implications of an avian‐style respiratory system for gigantism in sauropod dinosaurs

Perry, Steven F.; Christian, Andreas; Breuer, Thomas; Pajor, N; Codd, Jonathan R.

doi:10.1002/jez.517

Cited by 34 publications

(24 citation statements)

References 58 publications

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“…There is speculation based on computational and fossil evidence that this more efficient bird-style lung may have evolved in Sauropod Dinosaurs. The computational argument is offered by a mathematical model for ventilation with an 11-m-long trachea where the work of breathing becomes limiting in a bellows type of lung (66,279). The fossil evidence is the presence of pneumatic foramina in Sauropod skeleton that would be necessary for airflow to air sacs (368).…”

Section: Origin and Architecture Of The Mammalian Lungmentioning

confidence: 99%

Lung Structure and the Intrinsic Challenges of Gas Exchange

Hsia

Hyde

Weibel

2016

Comprehensive Physiology

158

137

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Structural and functional complexities of the mammalian lung evolved to meet a unique set of challenges, namely, the provision of efficient delivery of inspired air to all lung units within a confined thoracic space, to build a large gas exchange surface associated with minimal barrier thickness and a microvascular network to accommodate the entire right ventricular cardiac output while withstanding cyclic mechanical stresses that increase several folds from rest to exercise. Intricate regulatory mechanisms at every level ensure that the dynamic capacities of ventilation, perfusion, diffusion, and chemical binding to hemoglobin are commensurate with usual metabolic demands and periodic extreme needs for activity and survival. This article reviews the structural design of mammalian and human lung, its functional challenges, limitations, and potential for adaptation. We discuss (i) the evolutionary origin of alveolar lungs and its advantages and compromises, (ii) structural determinants of alveolar gas exchange, including architecture of conducting bronchovascular trees that converge in gas exchange units, (iii) the challenges of matching ventilation, perfusion, and diffusion and tissue-erythrocyte and thoracopulmonary interactions. The notion of erythrocytes as an integral component of the gas exchanger is emphasized. We further discuss the signals, sources, and limits of structural plasticity of the lung in alveolar hypoxia and following a loss of lung units, and the promise and caveats of interventions aimed at augmenting endogenous adaptive responses. Our objective is to understand how individual components are matched at multiple levels to optimize organ function in the face of physiological demands or pathological constraints.

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Section: Origin and Architecture Of The Mammalian Lungmentioning

confidence: 99%

Lung Structure and the Intrinsic Challenges of Gas Exchange

Hsia

Hyde

Weibel

2016

Comprehensive Physiology

158

137

View full text Add to dashboard Cite

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“…The difference between the endotherm and ectotherm BMR for the same body mass and temperature is substantial, emphasising the significant metabolic cost to being an endotherm. There is no need a priori to hypothesise a downregulation of metabolic rate with age (Pierson 2009) or a reduction of metabolic rate to avoid overheating at large sizes (Perry et al 2009). …”

Section: Large Dinosaurs As Warm Reptilesmentioning

confidence: 99%

Dinosaur Energetics: Setting the Bounds on Feasible Physiologies and Ecologies

Clarke

2013

The American Naturalist

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The metabolic status of dinosaurs has long been debated but remains unresolved as no consistent picture has yet emerged from a range of anatomical and isotopic evidence. Quantitative analysis of dinosaur energetics, based on general principles applicable to all vertebrates, shows that many features of dinosaur lifestyle are compatible with a physiology similar to that of extant lizards, scaled up to dinosaur body masses and temperatures. Sufficient metabolic scope would have been available to support observed dinosaur growth rates and allow considerable locomotor activity, perhaps even migration. Since at least one dinosaur lineage evolved true endothermy, this analysis emphasises that there was no single dinosaur physiology. Many small theropods were insulated with feathers and appear to have been partial or full endotherms. Uninsulated small taxa, and all juveniles, would presumably have been ectothermic, with consequent diurnal and seasonal variations in body temperature. In larger taxa inertial homeothermy would have resulted in warm and stable body temperatures, but with a basal metabolism significantly below that of living mammals or birds of the same size. It would appear that dinosaurs exhibited a range of metabolic levels to match the broad spectrum of ecological niches they occupied.

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“…Various theories on the posture and flexibility of the neck have been presented [8], [9], [11]–[15], with differing approaches leading to various implications for overall biology. Whilst heart size and output [16], [17], the structure of the respiratory system [18], [19], risk of predation, and intraspecific niche partitioning [13] are all affected by neck function, there are also major implications for sauropod diet and ecology [11]. Whilst neck posture and flexibility in most species has relatively little effect on their ecology due to their relatively short necks, sauropod necks can reach up to 15 m in length [20], meaning small differences in the angle at which the neck is held can lead to differing head heights of a metre or more.…”

Section: Introductionmentioning

confidence: 99%

Inter-Vertebral Flexibility of the Ostrich Neck: Implications for Estimating Sauropod Neck Flexibility

2013

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The flexibility and posture of the neck in sauropod dinosaurs has long been contentious. Improved constraints on sauropod neck function will have major implications for what we know of their foraging strategies, ecology and overall biology. Several hypotheses have been proposed, based primarily on osteological data, suggesting different degrees of neck flexibility. This study attempts to assess the effects of reconstructed soft tissues on sauropod neck flexibility through systematic removal of muscle groups and measures of flexibility of the neck in a living analogue, the ostrich (Struthio camelus). The possible effect of cartilage on flexibility is also examined, as this was previously overlooked in osteological estimates of sauropod neck function. These comparisons show that soft tissues are likely to have limited the flexibility of the neck beyond the limits suggested by osteology alone. In addition, the inferred presence of cartilage, and varying the inter-vertebral spacing within the synovial capsule, also affect neck flexibility. One hypothesis proposed that flexibility is constrained by requiring a minimum overlap between successive zygapophyses equivalent to 50% of zygapophyseal articular surface length (ONP50). This assumption is tested by comparing the maximum flexibility of the articulated cervical column in ONP50 and the flexibility of the complete neck with all tissues intact. It is found that this model does not adequately convey the pattern of flexibility in the ostrich neck, suggesting that the ONP50 model may not be useful in determining neck function if considered in isolation from myological and other soft tissue data.

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Implications of an avian‐style respiratory system for gigantism in sauropod dinosaurs

Cited by 34 publications

References 58 publications

Lung Structure and the Intrinsic Challenges of Gas Exchange

Lung Structure and the Intrinsic Challenges of Gas Exchange

Dinosaur Energetics: Setting the Bounds on Feasible Physiologies and Ecologies

Inter-Vertebral Flexibility of the Ostrich Neck: Implications for Estimating Sauropod Neck Flexibility

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