For three decades, researchers have been divided over the finding of new species of Tyrannosaurus rex. But a new study reveals that the two skeletons found in the early 2000s are not of new species of tyrannosaurs. The paleontologists have reached to a conclusion that the species were simply juveniles of the rex species. In order to put to rest this argument, the researchers had to closely study the skeletons named Jane and Petey. These skeletons were recovered from the Hell Creek Formation in North America near Jordan, Montana. These rocks are one of the most famous and intensively studied dinosaur fossil sites. Out of the two specimens, the more complete one was nicknamed Jane and the other one Petey. The fossils were named by the staff of the Burpee Museum of Natural History.
When found in the early 2000s, it was argued that they belong to pygmy tyrannosaurs called Nanotyrannus. To get clarity, researchers studied leg bones of the species to ascertain their ages. They took extremely fine slices of bone to study growth rings that put Petey and Jane at 15 and 14 years old. The size of blood vessel openings of the fossils also revealed that they were rapidly growing at the time of death. Had they been full grown adults, this vascularisation would not have been so prominent. The study by Holly Woodward at Oklahoma State University has been published in the journal Science Advances.
The study of Sue, one of the most complete and largest fossils of Tyrannosaurus rex skeletons found so far, revealed that it was around 30 years. Going by this, Jane and Petey were just adolescents and therefore there is no need to talk about new species to explain their small size. Woodward said that Tyrannosaurus rex is known to be a giant king of dinosaurs. “But we have no idea about how it got so huge,” he added. Given the change in their body, researchers believe that fed on varied prey during their different age groups.