By Will DunhamWASHINGTON, Jan 15 (Reuters) – There is no question that Tyrannosaurus rex got big. In fact, this fearsome dinosaur may have been Earth’s most massive land predator of all time. But the question of how quickly T. rex achieved its maximum size has been a matter of debate.A new study examining bone tissue microstructure in the leg bones of 17 fossil specimens concludes that Tyrannosaurus took about 40 years to reach its maximum size of roughly 8 tons, some 15 years more than previously estimated. As part of the study, the researchers identified previously unknown growth marks in these bones that could be seen only using polarized light.AdvertisementAdvertisementAdvertisementAdvertisement”This growth trajectory is more gradual than expected,” said paleohistologist Holly Woodward of the Oklahoma State University Center for Health Sciences, lead author of the study published this week in the journal PeerJ. “Rather than T. rex ratcheting up to adult size quickly, it spent a lot of its life at juvenile to subadult sizes.”The researchers scrutinized annual growth rings – akin to those present in tree trunks – in the Tyrannosaurus leg bones from the various specimens, which ranged from smaller juveniles to massive adults.”We also found that growth-ring spacing in individual T. rex was variable. T. rex had a flexible growth pattern. Some years it didn’t grow much, while other years it grew a lot,” Woodward said.”This likely depended on resou …
