Some like it hot! Some like it cold!

Controversy whether dinosaurs were warm blooded or cold blooded

            Since the discovery of dinosaurs it has been assumed they were lumbering cold blooded creatures. It wasn’t until the mid seventies that this idea was challenged by an undergraduate at Yale named Bob Bakker. He was the first paleontologist to mainstream this idea. With the advancement of technology scientists are now using O¹⁸/O¹⁶ ratios to help support endothermy. Opponents of this idea however are mounting evidence that respiratory turbinates which are commonly found in extant mammals and birds but not dinosaurs.

Figure 1: Respitory turinates of warm blooded animals and lack of turbinates in cold blooded animals (Morell,1996)

Definitions:

n Endothermic - Characterized by or formed with absorption of heat. (Webster.com)

n Ectotherms - A cold-blooded animal. (Webster.com)

n Bradymetabolic - An animal whose metabolism slows to a low level of activity when resting is called

n Tachymetabolic - An animal whose metabolism remains at a high level, burning calories and maintaining other metabolic functions at a high pace

n Respiratory Turbinates -   are structures (consisting mostly of cartilaginous sheets attached to bony ridges) inside the nasal cavities and in the respiratory

airstream.

References

Barrick, R. , Showers, W.J. 1995. Oxygen istope variability in juvenile dinosaurs

(Hypacrosaurus): evidence for thermoregulation. Paleobiology. 21(4) 552-560

Fischman, J. 1995. Were dinos cold blooded after all? The nose knows. Science Nov. 3 v

270, 735-737

Glut, D. (2002) Dinosaurs the encyclopedia supplement 2. McFarland and Compmany,

inc., Publishers.  86-94

Morell, V. (1996) A cold, hard look at dinosaurs. Discover. 97-108

O’Connor, M., Dodson, P.. 1999. Biophysical constraints on the thermal ecology if

Dinosaurs. Paleobiology. 25(3) 341-368

Seebacher, F. 2003. Dinosaur body temperature: the occurrence of endothermy and

ectothermy. Paleobiology 29(1) 105 -122