Movies such as Jurassic Park and the acclaimed BBC television series Walking with Dinosaurs portray long-necked dinosaurs as raising their necks vertically to browse from the tops of trees.
And while most dinosaur palaeontologists also believe long-necked dinosaurs - collectively known as sauropods - behaved this way, a leading Adelaide University researcher has just published new data which suggests otherwise.
Dr Roger Seymour, from Adelaides Department of Environmental Biology, has co-authored a paper in the prestigious Proceedings of the Royal Society in London, which argues it was physically impossible for sauropods to behave in this way. The paper argues that due to the sauropods possible heart size and metabolic rates, the only way they could have functioned on land was with a horizontal neck.
Dr Seymour based his findings on his research of the factors which determine heart size in animals. He has spent the past 24 years collecting data on heart morphology and arterial blood pressure in reptiles, birds and mammals to determine how blood pressure influences the thickness of the heart wall. His research is directed at understanding the evolution of vertebrate cardiovascular systems.
His research shows that heart size in all animals depends on two factors: the vertical distance of the head above the heart, and whether the animal was cold- or warm-blooded. For example, the giraffe has exceptionally high blood pressure and an enlarged heart because it has to pump blood up its long neck. Birds and mammals also have relatively large hearts because they are warm-blooded, while cold-blooded reptiles have low metabolic rates, low blood pressures and smaller hearts.
"We have determined that the left ventricle in a warm-blooded Barosaurus, for instance,
would have needed to weigh about 2000kg to pump the blood its brain needed," he
Contact: Dr. Roger Seymour