So far, all scientists have are some rough estimates of how big Tyrannosaurus rex might have been during its prehistoric heyday. But a U.S. scientist is currently hard at work at determining just how big the “terrible lizard” was, as she continues what could be the largest, most comprehensive study of T. rex bones to date.
For the purposes of this study, Oklahoma State University paleontologist Holly Ballard has been working with parts of T. rex skeletons sent by museums from different parts of the United States and Canada. According to Tulsa World, Ballard has been able to understand more about the life of these dinosaurs, using thin slices of bone to determine their age at the time of their death, their rate of growth, and other helpful pieces of information.
Speaking to Tulsa World, Ballard explained that animal bones always grow in layers, much like tree trunks add rings to show their age. That means a ring on a slice of bone could suggest a year of growth, with thicker rings suggesting that an animal is growing at a faster than usual pace.
“The spacing will tell you have much active growing there was from year to year,” Ballard said.
“The rings are starting to get more closely spaced near the edge. This is typical of larger animals, because when you’re young, you’re going to be growing a lot from year to year, but as you get older, you’re not growing as much from year to year. Think of us: When you’re in your 20s, you’re pretty much done.”
The Tulsa World report also referred to the skeleton of a T. rex that scientists dubbed “Sue,” which currently stands out as the largest such skeleton ever found, at a length of 40 feet. Sue is believed to have weighed between nine and 15 tons, and based on the dinosaur’s rib bones, the creature might have been around 28-years-old when it died. Still, that doesn’t answer the question of how big Tyrannosaurus rex could have grown, as it’s hard to estimate typical size range or growth patterns based on only one or two skeletons.
“It’s like people: No one is going to grow exactly the same from person to person, so if you have a single dinosaur specimen, you can’t infer that it’s growing like the entire species would have been growing,” Ballard explained.
Although Ballard’s study has yet to be completed, it has the potential to add to a growing body of scientific literature about the iconic Tyrannosaurus rex. In October, University of Hawaii paleontologist Steven Stanley theorized that T. rex’s ostensibly thin and puny-looking arms might have been “vicious weapons” with four-inch claws, allowing the dinosaur to easily tear apart its prey. According to the New York Post, Stanley’s research contradicted previous studies that explained T. rex’s small arms by suggesting they were used by the creatures to keep their partners close while mating.
As of now, Ballard is approximately halfway through the study, having taken samples from 15 juvenile T. rex fossils, with another 15 needed to get reliable results. She is also studying fossils from some of T. rex’s smaller relatives, such as Gorgosaurus and Albertosaurus, hoping to find out if there was something that prevented these dinosaurs from becoming as big as Tyrannosaurus rex. And it all boils down to the analysis of growth rings on the creatures’ bones, tracking their growth from childhood to adulthood and plotting the data on a graph.
The ultimate goal of the study is to come up with a definitive answer to the question of how big Tyrannosaurus rex could have gotten. But in order for that to happen, Ballard stressed that she needs to find an adult of the species in her sample set, something that she believes she is getting close to after having studied some bones with closely spaced rings.
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