Baby tyrannosaurs were surprisingly small

While tyrannosaurs were some of the largest predators of all time, a new study from the University of Edinburgh reveals that their babies were surprisingly small. Scientists have discovered that baby tyrannosaurs were no bigger than a medium-sized dog when they took their first steps.

The study was focused on the fossils of tyrannosaur embryos. The remains are providing brand new insight into the early development of tyrannosaurs, which weighed as much as eight tons and grew up to 40 feet in length.

The team created 3D scans of two tiny one-inch dinosaur bones unearthed in Canada, including a jaw bone and a claw. 

The scans revealed that the delicate remains belonged to baby tyrannosaurs – cousins of Tyrannosaurus rex. The researchers discovered that the jaw bone contained distinctive tyrannosaur features, such as a pronounced chin.

Based on the size of the fossils, the baby tyrannosaurs were around three feet long when they hatched. Study lead author Dr. Greg Funston said the bones can teach us much about their size and appearance.

While tyrannosaur eggs have never been found, the new research indicates that they would have been around 17 inches long. This finding could aid efforts to recognize such eggs in the future and gain greater insights into the nesting habits of tyrannosaurs, explained the researchers.

The earliest developmental stages of tyrannosaurs remain a mystery to scientists. This is because the vast majority of tyrannosaur fossils that have been uncovered belonged to adults or older juveniles.

“These bones are the first window into the early lives of tyrannosaurs and they teach us about the size and appearance of baby tyrannosaurs,” said Dr. Funston. “We now know that they would have been the largest hatchlings to ever emerge from eggs, and they would have looked remarkably like their parents – both good signs for finding more material in the future.”

The study is published in the journal Canadian Journal of Earth Sciences.

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By Chrissy Sexton, Earth.com Staff Writer