Respiratory and Reproductive Paleophysiology of Dinosaurs and Early Birds

  title={Respiratory and Reproductive Paleophysiology of Dinosaurs and Early Birds},
  author={John A. Ruben and Terry D. Jones and Nicholas R. Geist},
  journal={Physiological and Biochemical Zoology},
  pages={141 - 164}
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… 
Dinosaur Physiology: Were Dinosaurs Warm‐blooded?
D dinosaurs were most likely ectothermic, with resting and maximal metabolic rates that were lower than those of modern mammals or birds, however, given the favourable Mesozoic climatic conditions, most dinosaurs were probably able to maintain high, constant body temperatures through behavioural or inertial thermoregulation.
The Evolution of Endothermy in Terrestrial Vertebrates: Who? When? Why?
The fossil record of nonmammalian synapsids suggests that at least two Late Permian lineages possessed incipient respiratory turbinates, but this suggests that dinosaurs and nonornithurine birds generally lacked the capacity for high, avian‐like levels of sustained activity, although the aerobic capacity of theropods may have exceeded that of extant ectotherms.
Comparative digestive physiology of archosaurs with notes on bird origins
Coprolites of early archosaurs contain undigested bones, which suggests a short digestion time and higher metabolic rates than in extant crocodiles, and implies reappearance and strong development of a specific stomach functionality that either had been already lost in the theropod dinosaurs or was never present in their lineage.
Do feathered dinosaurs exist? Testing the hypothesis on neontological and paleontological evidence
It is suggested that Aves plus bird‐like maniraptoran theropods (e.g., microraptors and others) may be a separate clade, distinctive from the main lineage of Theropoda, a remnant of the early avian radiation, exhibiting all stages of flight and flightlessness.
Respiratory Evolution Facilitated the Origin of Pterosaur Flight and Aerial Gigantism
Various lines of skeletal evidence indicate that pterosaurs had a highly effective flow-through respiratory system, capable of sustaining powered flight, predating the appearance of an analogous breathing system in birds by approximately seventy million years.
Reproduction in Mesozoic birds and evolution of the modern avian reproductive mode
Significant changes between enantiornithine birds and neornithines include an additional increase in relative egg size and sediment-free incubation, and the latter permitted greater adult–egg contact and likely more efficient incubation.
An Intermediate Incubation Period and Primitive Brooding in a Theropod Dinosaur
This tooth age suggests a Troodon incubation period of 74 days, falling midway between avian and reptilian values predicted by the Troodon egg mass, which concurs with a suite of features in oviraptorosaurs and troodontids that appear dependent upon both adult body and incubation temperatures elevated over ambient conditions.
The physiology of dinosaurs: circulatory and respiratory function in the largest animals ever to walk the earth.
  • D. Pierson
  • Environmental Science
    Respiratory care
  • 2009
Diverse lines of evidence suggest that the giant sauropods were probably warm-blooded and metabolically active when young, but slowed their metabolism as they approached adult size, which diminished the load on the circulatory system.
A distinct dinosaur life history?
Oviparity and parental care, predicted for dinosaurs by their extant phylogenetic bracket, have the least fossil support and the author cautions against overextending parsimonious interpretations to extinct taxa with the risk of obscuring novel or intermediate behaviours.
A large enantiornithine bird from the Lower Cretaceous of China and its implication for lung ventilation
The presence of uncinate processes, bicapitate and forked vertebral ribs, sternal ribs that were all of similar length, as well as the location of parapophyses and diapophyses on the thoracic vertebrae, may imply a rigid and volume-constant lung, and less efficient lung ventilation in enantiornithines.


  • Robert T Barker
  • Environmental Science, Geography
    Evolution; international journal of organic evolution
  • 1971
The fossil evidence strongly suggests that no small dinosaurs ever existed in either Jurassic or Cretaceous, and the most convincing proof of the lack of truly small dinosaur species is their absence in the carefully studied microvertebrate concentrates.
Metabolism of leatherback turtles, gigantothermy, and thermoregulation of dinosaurs
It is indicated that leatherbacks can use large body size, peripheral tissues as insulation, and circulatory changes, to maintain warm temperatures in the North Atlantic and to avoid overheating in the tropics.
  • W. J. Hillenius
  • Biology, Environmental Science
    Evolution; international journal of organic evolution
  • 1994
The presence of respiratory turbinals in these advanced mammallike reptiles suggests that the evolution of “mammalian” oxygen consumption rates may have begun as early as the Late Permian and developed in parallel in therocephalians and cynodonts.
A nesting dinosaur
The specimen described here is the first preserved well enough to determine its precise relationship with the nest, and provides the strongest evidence yet for the presence of avian brooding behaviour in non-avian dinosaurs.
Dinosaur Reproduction and Parenting
Non-avian dinosaur reproductive and parenting behaviors were mostly similar to those of extant archosaurs, but some reproductive behaviors, once thought exclusive to Aves, arose first in non-avians.
Haemothermia or Archosauria? The interrelationships of mammals, birds and crocodiles
Several lines of evidence all lead to the conclusion that the traditional theory of a relationship between birds and crocodiles, vis a vis mammals is substantially the better supported.
The Metabolic Status of Some Late Cretaceous Dinosaurs
Analysis of the nasal region in fossils of three theropod dinosaurs and one ornithischian dinosaur showed that their metabolic rates were significantly lower than metabolic rates in modern birds and mammals.
The Evolutionary History of Sauropod Dinosaurs
Forked chevrons, which have played such an important role in previous studies of sauropod phylogeny, are here considered to have evolved twice within the Sauropoda, which may reflect a correlation between chevron shape and the use of the tail as a weapon within these twosauropod families.
The evolution of endothermy in mammals and birds: from physiology to fossils.
  • J. Ruben
  • Environmental Science, Biology
    Annual review of physiology
  • 1995
Endothermic warm­ bloodedness or, more correctly, endothermic homeothermy generally results from a combination of high resting, aerobically supported heat production rates in virtually all soft tissues, and insulation sufficient to retard excessive heat loss.