From the Houston Chronicle:
Once they made it to about age 2 they could take on just about any other predator and had very little mortality until they reached sexual maturity in their teens, researchers reported in the current issue of the journal Science.
“Survivorship stabilized at between 2 (percent) and 4 percent per year until midlife, at which point they went through an honest-to-God midlife crisis,” said Gregory Erickson, who teaches comparative anatomy at Florida State University.
His team studied the remains of several species of North American tyrannosaur, including Albertosaurus, Tyrannosaurus, Gorgosaurus and Daspletosaurus.
They concluded that mortality could be high for youngsters, both because some didn’t have much resistance to disease and because of predators.
But after about age 2, some 70 percent survived to reach sexual maturity between 13 and 16, when mortality increased to 23 percent a year. Their potential lifespan reached to the late 20s and early 30s.
“I think love was a dangerous game for tyrannosaurs,” said Erickson.