Thermal Regulation in Sail Lizards

  title={Thermal Regulation in Sail Lizards},
  author={Cherrie D. Bramwell and Peter Fellgett},
THE extinct Order Pelycosauria contained several genera of reptiles characterized by extreme elongation of the neural spines of the vertebrae, which in life supported an area of membrane forming a “sail”1–3. Dimetrodon grandis was the end form of an evolutionary series of pelycosaurs that had tended to develop increasingly large sails2. Many suggestions have been made about the function of the sail, as camouflage among reeds while it waited for prey, for sexual display, or literally as a sail… 

Natural environment and thermal behaviour of Dimetrodon limbatus.

Aerodynamics and thermoregulatory function of the dorsal sail of Edaphosaurus

Wind tunnel modeling of air flow over a thin sail with laterally projecting cross-bars supports a thermoregulatory interpretation of the sail of Edaphosaurus, and measurements of heat flow in an instrumented model show that cross- Bars increase heat loss from the sail.

A new long-spined dinosaur from Patagonia sheds light on sauropod defense system

The long, anteriorly bent spines of this new dicraeosaurid sauropod, Bajadasaurus pronuspinax gen. et sp.

Neural spine elongation in dinosaurs: sailbacks or buffalo-backs?

  • J. Bailey
  • Environmental Science
    Journal of Paleontology
  • 1997
It is argued here that the neural spines of Ouranosaurus, Spinosaurus, and several other long-spined dinosaurs favor bison-like humps rather than sails, and the insulation properties of humps favor gigantothermy, the most likely thermobiological model for large dinosaurs.

Antiquity of “Sail-Backed” Neural Spine Hyper-Elongation in Mammal Forerunners

A new hyper-elongated neural spine belonging to the earliest ophiacodontid synapsid Echinerpeton intermedium is described from the Pennsylvanian-aged deposits of Florence, Nova Scotia, unveiling the rapid convergence and repeated evolution of the “dorsal sail” morphology in Synapsida.

Does mutual sexual selection explain the evolution of head crests in pterosaurs and dinosaurs

It is concluded that mutual sexual selection presents a valid hypothesis for the functions of ornithodiran cranial crests and the integration of mutualSexual selection into future studies is critical to the authors' understanding of OrnithodIRan ecology, evolution and particularly questions regarding sexual dimorphism.

The Evolution of Endothermy in the Phylogeny of Mammals

  • B. McNab
  • Environmental Science, Biology
    The American Naturalist
  • 1978
It is concluded that many of the characteristics that distinguish mammals from reptiles, including endothermy, viviparity, and even lactation, may be related to the marked decrease in body size that occurred in the evolution of mammals from advanced therapsids.


  • 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.

Nocturnality in synapsids predates the origin of mammals by over 100 million years

Recognizing the complexity of diel activity patterns in non-mammalian synapsids is an important step towards a more nuanced picture of the evolutionary history of behaviour in the synapsid clade.

Nasal turbinates and the evolution of mammalian endothermy

Results suggest that the evolution of "mammalian" oxygen consumption rates may have begun as early as the Late Permian, 260 million years ago, and developed largely independently in therocephalians and cynodonts.



Notes on the Permo-Carboniferous Reptile Dimetrodon

  • A. Romer
  • Chemistry
    The Journal of Geology
  • 1927
1. A nearly complete postcranial skeleton of the Permo-Carboniferous reptile Dimetrodon is described and figured. The structure and possible function of the spines are discussed, and a mechanical