Dinosaur size

From PhiloWiki

Why did dinosaurs get so big? How did they?

Dinosaurs could grow large due to inertial homeothermy

Some scientists had assumed that dinosaurs, which evolved from reptiles, were cold blooded (ectotherms), whereas others thought that dinosaurs, like mammals and birds, might have been warm blooded (endotherms). Still others argued that while most dinosaurs had a metabolism similar to contemporary reptiles, the large dinosaurs managed a higher, more-constant body temperature through thermal inertia, which is how modern alligators, Galapagos tortoises, and Komodo dragons retain heat. Thermal inertia allows the body to approach homeothermy, or constant body temperature, when the ratio of body mass to surface area is high enough. If this "inertial homeothermy" hypothesis is correct, dinosaur body temperature should increase with body size.

The researchers used a model that provided estimates of dinosaur body temperature based on developmental growth trajectories inferred from juvenile and adult fossil bones of the same species. The model predicts that dinosaur body temperature did increase with body mass, and that large dinosaurs had body temperatures similar to those of modern birds and mammals, while smaller dinosaurs' temperatures were more like contemporary reptiles.

Math and fossils resolve a debate on dinosaur metabolism from Public LIbrary of Science