The biggest dinosaurs reached their enormous proportions by growing faster than almost any animal that has ever lived, a new analysis of fossilized bones indicates. In the July 26 issue of Nature, paleontologists from Florida State University estimate that the giant apatosaurus, formerly known as brontosaurus, put on more than 30 pounds a day at the height of its adolescent growth spurt.
The discovery further discredits the old image of dinosaurs as little more than overgrown reptiles. It suggests that the animals developed some advanced metabolic tricks, such as warmbloodedness, to maintain their rapid growth rates. A full-grown apatosaurus, which would have weighed 25 tons, would have grown to adulthood in 12 to 20 years, they estimate.