T. rex had huge growth spurts, but other dinos grew 'slow and steady'

Tyrannosaurus rex was one of the biggest meat-eating dinosaurs of all time—it measured up to 42 feet long from snout to tail and would have weighed in at around 16,000 pounds. And it wasn't alone—some of its less-well-known cousins could reach nearly the same size. Scientists have previously shown that T. rex got so big by going through a huge teenage growth spurt, but they didn't know if that was true for just tyrannosaurs, just them and their close relatives, or perhaps all big bipedal dinosaurs. By cutting into dinosaur bones and analyzing the growth lines, a team of researchers got their answer: T. rex and its closest relatives had an awkward adolescence during which they got huge, while its more distant cousins in the allosauroid group kept on growing a little bit every year.