Dinosaurs May Have Been Smaller Than Previously Thought

http://www.sciencedaily.com/releases/2009/06/090621195620.htm

ScienceDaily (June 22, 2009) — The largest animals ever to have walked the face of the earth may not have been as big as previously thought, reveals a paper published June 21 in the Zoological Society of London’s Journal of Zoology.

Scientists have discovered that the original statistical model used to calculate dinosaur mass is flawed, suggesting dinosaurs have been oversized.

Widely cited estimates for the mass of Apatosaurus louisae, one of the largest of the dinosaurs, may be double that of its actual mass (38 tonnes vs. 18 tonnes).

"Paleontologists have for 25 years used a published statistical model to estimate body weight of giant dinosaurs and other extraordinarily large animals in extinct lineages. By re-examining data in the original reference sample, we show that the statistical model is seriously flawed and that the giant dinosaurs probably were only about half as heavy as is generally believed" says Gary Packard from Colorado State University.

The new predictions have implications for numerous theories about the biology of dinosaurs, ranging from their energy metabolism to their food requirements and to their modes of locomotion.