Teenage T. rex was already chomping on prey — ScienceDaily

In a research printed final week within the peer-reviewed journal Peerj -- the Journal of Life and Environmental Sciences, UWO scientists reported proof juvenile T. rex fed on a big plant-eating dinosaur, though it lacked the bone-crushing talents it will develop as an grownup.

While learning fossils from an Edmontosaurus -- a plant-eating Hadrosaurid or duck-billed dinosaur, UWO vertebrate paleontologist Joseph Peterson observed three giant, v-shaped, chew marks on a tail bone and puzzled, "Who made these?"

Peterson knew that T. rex -- a member of the meat-eating dinosaur suborder generally known as Theropoda -- was "a likely culprit."

"We suspected that T. rex was responsible for the bit marks, because in the upper Cretaceous rock formation, where the hadrosaur was discovered, there are only a few carnivorous dinosaurs and other reptiles in the fossil record. Crocodile fossils are found there, but such a crocodile would have left tooth marks that are round rather than the elliptical punctures we found on the vertebra," Peterson defined.

"There also were small Velociraptor-like dinosaurs, but their teeth are too small to have made the marks. Finally, an adult T. rex would have made punctures that would have been too large! That's when we started considering a juvenile tyrannosaur."

To check the speculation, Peterson and geology scholar Karsen Daus, of Suamico, coated the fossil with a silicon rubber to make a silicone peel of the puncture marks.

They discovered that the size of the "teeth" higher matched a late-stage juvenile T. rex (11 to 12 years) than an grownup (roughly 30 years).

"Although this T. rex was young, it really packed a punch," Peterson stated.

"This is significant to paleontology because it demonstrates how T. rex -- the most popular dinosaur of all time -- may have developed changes in diet and feeding abilities while growing," he stated. "This is part of a larger, ongoing research initiative by many paleontologists to better understand how T. rex grew and functioned as a living creature over 65 million years ago."

Most theropod feeding traces and chew marks are attributed to adults; juvenile tooth marks hardly ever have been reported within the literature, he added.

"We really are in the 'Golden Age' of paleontology," Peterson stated. "We are learning more now than we ever thought we would know about dinosaurs. And, we're learn more about how they grew up."

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