Researchers have discovered the first baby tyrannosaur fossils in Alberta and Montana.
Experts say the fossils are a rare discovery, as little is known about young tyrannosaurs and their development, according to a study published in the Canadian Journal of Earth Sciences on Monday.
The study, led by Greg Funston, was based on two fossils: a small toe claw found in Morrin, Alta., and a small, lower jawbone found in Montana.
Tyrannosaurs have been well-researched but fossils from tyrannosaur eggs or embryos have never been found — until now.
“What this does is give us a starting point that we didn’t have,” said Mark Powers, a University of Alberta PhD student and second author on the study.
“We had partway of their growth spurt and we didn’t really have where they originated. To find specimens like this, which is definitively a tyrannosaur in the shell or before it hatched, it says something about that development.”
What do the discoveries mean?
The unprecedented finds offer a lot of information to researchers.
Using a 3D scan of the fossils and measurements of the bones, researchers were able to find out more about the size of the hatchlings and prove that the specimens are of unborn tyrannosaurs.
The 71.5 million-year-old claw found in Alberta has what Powers called “a cartilage cone” on the back of the claw, which means the area hadn’t yet turned to bone and was still developing.
The roughly 75 million-year-old jawbone found in Montana had triangular teeth with shallow roots, confirming they were the first generation teeth of the tyrannosaur.
“This fits with a lot of other discoveries and embryonic studies of birds and other dinosaurs found in the shell so we do suspect that it is an embryonic individual compared to a hatched one,” Powers said.
The location of these fossils is also telling.
The claw was found after a large sediment was taken from a dig expedition in Alberta several years ago, Powers said.
Generally, smaller dinosaur remains are harder to come by.
Smaller fossils would have been more susceptible to the flowing rivers and flood plains of the cretaceous period, compared to larger dinosaur remains which are often buried deep and preserved in sediment, Powers said.
The areas where the fossils of the young dinosaurs were found are now possible locations for other important discoveries, according to one professor.
“We don’t have very much of a skeleton by any means, these are relatively scrappy bits. But because we know the area where it seems tyrannosaurs may have been making their nests, we know to go back to that spot and go over with a fine-tooth comb and find more and more stuff,” said Scott Persons, professor of paleontology at the College of Charleston in South Carolina.
“I think undoubtedly that is going to happen so eventually that great prize of actually finding a tyrannosaur egg is going to happen.”