These sleek predatory dinosaurs really are teenage T. rex

Fossils thought to belong to juvenile Tyrannosaurus rex suggest that the bone-crushing behemoths were sleek, fleet-footed predators with knife-like teeth in their teenage years.PUBLISHED January 1, 2020Sixty-six million years ago, the ground of western North America trembled with the footfalls of a tyrant: Tyrannosaurus rex. rex remains pulled from the region’s Cretaceous-period rocks, scientists have had few clues about how the celebrity dinosaur grew from a hatchling to a gargantuan predator—until now.In a study published in Science Advances on Wednesday, researchers reveal a stunningly detailed analysis on cross-sections of bone from juvenile tyrannosaurs. In the latter case, the fossils offer a rare glimpse at an important developmental stage in the life of this dinosaur icon.“There’s still a lot to learn about dinosaurs, even a dinosaur as famous as Tyrannosaurus rex,” says lead study author Holly Woodward, a paleontologist at the Oklahoma State University Center for Health Sciences. rex] had to grow fast to go from a hatching probably no bigger than a pigeon into an adult larger than a bus, but we don't know a lot about how it grew during its teenage years,” Steve Brusatte, a paleontologist at the University of Edinburgh who reviewed the study, says in an email.Enter Woodward, whose childhood fascination with microscopy led her to study the tiny structures preserved in dinosaur bones. rex].”Looking ahead, Woodward is adding data to an even bigger study of tyrannosaur growth, to nail down whether it’s possible to model the dinosaurs’ growth patterns based on the fragmentary fossil record.