The Outsized Influence of Teen T. Rex and Other Young Dinosaurs
A deep dive into dinosaur data suggests that teenage T. rexes and other juvenile carnivores shaped their ecosystems.
Adolescence is a time of great change for most of us. But it was particularly volatile for young T. rexes. Before they became fearsome, bone-crushing adults, they had to pass through a number of stages — two-foot hatchling, gangly preteen, bulky young adult. At each phase, they hunted different prey and filled different niches.
As a new study in Science reveals, juvenile T. rexes and the youth of other large carnivores called megatheropods transformed their communities as they fumbled through their own physical changes. Their rapid shifts in size and roles shaped their ecosystems, the study suggests, and could help to explain some of the perplexing mysteries of dinosaurdom, from the relative lack of species diversity to the strange preponderance of huge body sizes.
Considering dinosaurs ruled the planet for 179 million years, there were fewer distinct species than you might expect. While today’s world is positively fuzzy with mammals — at the moment, nearly 7,000 different types — we only know of about 1,500 non-avian dinosaur species, said Kat Schroeder, a Ph.D. student at the University of New Mexico and a co-author of the new paper.
There are also “some very weird things about their mass distribution,” Ms. Schroeder said. Within contemporary animal classes, small-bodied species tend to vastly outnumber big ones. (For instance, there are currently twenty species of elephant shrew, and just three species of elephant.) But for dinosaurs, it’s the opposite: “Most of them are large,” she said.
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