Fossil potential Tyrannosaurus embryos indicate that giant apex predators began with a mouse-sized skull.
The conclusion came after the author of the study found a toe nail from a baby Tyrannosaurus in Alberta, Canada in 2017. This led to the analysis of the previously known baby Tyrannosaurus mandible found in Montana in 1983. The surrounding rock, which has never been properly studied. But now, analysis of both fossils reveals all sorts of secrets about these baby beasts.
“These are very rare discoveries and the first in the world,” Gregory Fanston, a senior researcher at the University of Edinburgh in Scotland, told Live Science in an email. “All kinds of juvenile tyrannosaurus are extremely rare, and so far no bones suspected to be embryos have been found.”
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The study, which has not yet been published in a peer-reviewed journal, was presented online on Tuesday (October 13) at the Annual Meeting of the Society of Vertebrate Animals. This annual meeting has been virtualized this year by COVID-19. Pandemic..
The tiny 1.1 inch (2.9 cm) long Tyrannosaurus mandible still has eight small teeth. Being caught in the surrounding rocks, researchers scanned the mandible with a particle accelerator, allowing them to image fossils without excavation. Despite the miniature size of the mandible, “it looks amazing like the jaws of other young Tyrannosaurus,” Fantston said. “There is a deep groove on the inside and a unique jaw, both of which distinguish Tyrannosaurus from other carnivores. dinosaur.. “
These features helped other paleontologists to convince other paleontologists that the mandible really belongs to Tyrannosaurus. “We can see that these features can be used to identify Tyrannosaurus, no matter how immature they are.” He was not involved in the study, but went to live science at Yale University, where he attended a presentation at the conference. Told.
The teeth of the mandible are not fully developed, especially one tooth, which provides a clue that this fossil may belong to the early Tyrannosaurus. That is, the little Tyrannosaurus would have died before it hatched.
“One of the tooth sockets, a replacement tooth has been developed, but it’s an unusual method. Usually, the replacement tooth is just below the old tooth and eats at the root to release the old tooth.” Said Phanston. “In our case, the replacement tooth is next to the old tooth and there is no evidence of root collapse. This style of replacement was recently found in the first generation teeth of reptile embryos.”
(The fossil toenail may come from the embryo because one surface wasn’t completely formed, Fanston said.)
It is a mystery as to which Tyrannosaurus these fossils come from, but some of the famous predators in this group include: Tyrannosaurus Rex, Gorgosaurus And Albertosaurus.. But even without knowing the genus, “finding the remains of a very young Tyrannosaurus is very exciting,” said a PhD student in biology at the University of New Mexico who was not involved in the study but met. Said Cat Schroeder, who attended the presentation. Embryo fossils are rare, she told Live Science by email. “Dinosaurs would have been under threat of predation from egg-stealing mammals before they were born, and if this baby Tyrannosaurus hatched, the dinosaurs would have had to avoid them. Eat on Dromaeosaurus. Be (Velociraptor-Like a dinosaur), an old Tyrannosaurus, crocodile And maybe even Giant pterosaur.. ”
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Much more is known about Tyrannosaurus over two years ago. For example, a study published in a journal in June. PeerJThorough analysis by paleontologists T. RexGrowth from A small toddler hugging an adult.. Other Tyrannosaurus also have extreme growth patterns, “not as heavy as domestic cats, and grow to the size of an elephant in about 15 years,” Schroder said.
Fanston said researchers probably haven’t found Tyrannosaurus eggshells yet, so perhaps these dinosaur kings laid soft-shelled eggs that didn’t fossilize well. This is not unprecedented. Earlier this year two the study Nature published in the journal Triceratops-Like a dinosaur Protoceratops Sauropodomorpha with a long neck Mussaurus Probably laying Eggs with soft shellsSo was the marine reptile Mosasaurus.
“There is no direct evidence of these soft-shelled eggs yet, but these clues tell us that we should start looking,” Fanston said.
Originally published in Live Science.