Were large dinosaurs hot-blooded or cold-blooded? The topic is reviewed in a new book, edited by University of Queensland researchers.
Professor Gordon Grigg and UQ colleagues in the School of Life Sciences conducted an Australian Research Council-funded project looking at the implication of large size on body temperature in reptiles.
The work features in a new book, Crocodilian Biology and Evolution, edited by Professor Grigg, Dr Frank Seebacher and Dr Craig Franklin (Surrey Beatty and Sons, Sydney).
Because there are no extant dinosaurs to provide the definitive answer about dinosaur body temperatures, the researchers looked at their closest living relatives, the large estuarine or saltwater crocodiles, as models for their thermal relations.
Using radiotelemetry and biophysical modeling, Professor Grigg, Dr Seebacher and Ms Lyn Beard studied 30 crocodiles weighing from several kilograms to a tonne. They discovered that the larger the crocodile, the more stable the temperatures.
However, these could still vary from seasons to season. The average body temperature tended to be warmer as the size of the reptile increased, but the scientists were confident that crocodiles were without metabolic heat production, such as in birds and animals.
“The work has shown that very large reptiles could have had a warm and stable body temperature throughout the year, and at quite high latitudes, without having a high metabolism,” Professor Grigg said.
“Large crocodiles influenced their body temperature by basking in winter and seeking shade in summertime. We believe large dinosaurs in low latitudes also had to be near water or have access to forest cover.”
The book, Crocodilian Biology and Evolution is the proceedings of an international scientific conference on crocodiles held at UQ in 1998. Thirty-five of the papers presented at the conference led to manuscripts accepted for this volume. Topics range from crocodilian palaeobiology and phylogenetics to physiology and ecology.
The University of Queensland has been a focal point for research on the Australian estuarine crocodile for the past 15 years and this provided the stimulus for the conference. Professor Grigg and Associate Professor Craig Franklin have been conducting work on the remarkable heart of the crocodile. Professor Grigg said crocodiles had the most extraordinary and fascinating heart of all living vertebrates, with a complicated capacity for shunting blood away from the lungs. Dr Franklin and Dr Axelsson published a paper on teeth-like heart valves in the crocodile heart in the prestigious international journal Nature in 2000.
Media: For further information, contact Professor Gordon Grigg, telephone (07 3365 2470) or Dr Craig Franklin (telephone 07 3365 2355).
