Mortality rates among the tyrannosaurs

"Survivorship stabilized at between two and four percent per year, until midlife, at which point they went through an honest-to-God midlife crisis," Gregory M. Erickson, who teaches comparative anatomy at Florida State University, said in a telephone interview.

Crisis in this case entailing not angst but annihilation.

His team studied the remains of several species of North American tyrannosaur, including Albertosaurus, Tyrannosaurus, Gorgosaurus and Daspletosaurus. The researchers used growth rings in bones to calculate the mortality rates for the animals over their lifetimes.

Erickson concluded that mortality could be high for youngsters, because some didn't have much resistance to disease and because of predators. . .

But after about age two, some 70 percent survived to reach sexual maturity — between 13 and 16, when mortality increased to 23 percent a year. Tyrannosaur lifespans reached to the late 20s and early 30s.

Read the rest at Discovery News.

Posted by David on July 19, 2006 11:10 AM