A recent study found that baby tyrannosaurs were a Broder Collie dog's size when they took their first steps. Paleontologists from the University of Edinburgh created 3D scans of two tiny 1-inch dinosaur bones from Canada. The jaw bone and claw bone were both from embryo tyrannosaurs, wherein the team determined that the tyrannosaur would have been about 3 feet long when born.

The remains are the first-known fossils of tyrannosaur embryos. The researchers believe that it would also have a typical tyrannosaur protruding jawline when it hatched. The small size of baby tyrannosaur surprised the scientists, given that they could reach up to 40 feet as an adult.

Bones Are the Window to the Early Lives of Tyrannosaurs

In the Jurassic Park series, baby dinosaurs were smaller than the size researchers found them to be. They said that the hatchlings must have been the size of a Broder Collie dog, BBC reported.

"These bones are the first window into the early lives of tyrannosaurs, and they teach us about the size and appearance of baby tyrannosaurs," study lead author Dr. Greg Funston of the university's School of GeoSciences said.

"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," he added.

According to the researchers, the tyrannosaurs once lived in what is now North America on the once island continent known as Laramidia 68 to 66 million years ago. These dinosaurs were known as the dominant carnivores of their time, which garnered interest in the popular and scientific fields.

However, they could only find fossils of an adult, and juvenile dinosaurs, which left a black spot on what were these dinosaurs looked like when they hatchlings during their early development.

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How Big Are the Tyrannosaur Eggs?

According to MailOnline, the team created a series of 3D scans from the tiny bone fragments they collected, which are the 1-inch jaw bone and claw bone, to get a picture of the size of baby dinosaurs. The researchers also estimated the size of the tyrannosaur eggs, which were 17 inches (43 centimeters) long.

The researchers said that the discovery could lead to recognizing tyrannosaur eggs in the future to gain insight into the nesting habits of tyrannosaurs in the past. The fragments can give them information as to what dramatic changes the dinosaur underwent as it ages.

But since they only found limited bone fragments, there is also only a limit to what the team could tell about the bones' developmental history. However, the team also noted enough bone fragments that they can compare with other embryo fossils from other dinosaurs that the fossils they recently discovered were from pre-hatched infants.

Moreover, the rarity of tyrannosaurid embryonic material and the absence of eggshell at nesting sites baffled researchers.
Further investigation is needed to know why their absence when current evidence suggests that tyrannosaurid perinates should be present in nesting sites of other dinosaurs.

They published their findings in the Canadian Journal of Earth Sciences.

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