“Dinosaurs had such high metabolisms, so they needed a lot of energy to survive,” says Mike D’Emic, of Adelphi University, who wasn’t involved in this study. In fact, some dinosaurs changed so much throughout their lifetime that younger individuals can be mistaken for different species, which has even led to some pretty intense scientific argument. This kind of niche partitioning between life stages is seen in many animals, past and present, including lots of other dinosaurs. “The juveniles would have likely just run after their prey and wear it down, more like how modern wolves hunt.” “I suspect the adult tyrannosaurs, being roughly equal size or bigger to many of their likely prey species, would have tried to get as close as possible to any prey item and then try to overpower it, like the largest cats: lions and tigers,” Bykowski explains. rex-may have essentially acted as two-predators-in-one. With adults and young adults living and hunting in different ways, tyrannosaurs-particularly T. “In the absence of another large competitor, Tyrannosaurus ‘spread out’ ecologically while Daspletosaurus was more restricted.” “When Daspletosaurus lived, it shared its ecosystem with another large tyrannosaur: Gorgosaurus Tyrannosaurus lived alone on top of its ecosystem,” he says. Bykowski suspects this relates to the dinosaurs’ surroundings.

This study found that Tyrannosaurus, the latest and largest species in the family, experienced more intense ontogenetic change than its older cousin Daspletosaurus. It also turns out not all tyrannosaur development is equal. By changing their lifestyle over the course of development, these dinosaurs could limit how much they competed for resources with other members of their own species. You may be a fearsome carnivore, but if there’s one creature you don’t want to fight for your food, it’s a 40-foot adult. What’s the point of all this dramatic change? Well, imagine being a young tyrannosaur, already an impressive 20 feet long. According to Bykowski, “that suggests there might have been a change in how these animals used their mouths and teeth to consume and likely catch prey.” Their teeth shifted from being narrow and blade-like to being more rounded, like spikes, and their jaws grew proportionately shorter and beefier. Whether these predators were doing their hunting alone or in groups is still unknown.Īs they grew, tyrannosaurs’ bite changed, too. “ might have been more apt to run down prey as opposed to ambushing and over-powering it as adults,” says Bykowski, who presented his research last month at the annual meeting of the Society of Vertebrate Paleontology. This probably reflects a difference in hunting strategy. Proportions of their leg bones were comparable to those of fast-running animals today, while the adults had stockier limbs better suited to support a heftier body (think horse versus elephant). The jawbone of a juvenile Tyrannosaurus at the Burpee Museum of

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