Teenage T. Rex Had

Monster Growth Spurt

* Turns out the teenage Tyrannosaurus rex was a lot like a teenage kid: an eating and growing machine.

New research shows that the giant dinosaur had a growth spurt between the ages of 14 and 18. During those years, it put on about five pounds a day. That means that over four years, T. rex gained about 7,300 pounds. An adult weighed about 11,000 pounds. Most T. rexes probably died before their 30th birthday, says a study published today in the journal Nature.

Scientists wanted to answer the question nearly everyone has about dinosaurs: How did they get so big? One theory is that they grew slowly over many years, like ancient crocodiles. The other, which the study supports, is that they grew very quickly for a short time.

The research also may provide clues about whether the bone-crushing carnivores were predators or scavengers. One theory is that T. rexes were predators when they were young and very fast, hunting down prey and then letting bigger, slower adults come in for the kill.

What isn't in doubt is that these dinos were ferocious killers. T. rex "could eat a human being in probably two bites," said Thomas Holtz Jr. of the University of Maryland.

The mighty jaw of the T. Rex.