How do you calculate the age of a dinosaur? You can use growth rings, as you do with trees. Even the bones of dinosaurs, in fact, bear the signs of progressive growth due to age: this is how, for example, we have established that Tyrannosaurus rexthe most famous dinosaur in the world, continued to grow until he was 25 years old.
A fact that now needs to be revised, and quite a bit: a new study, published on PeerJupdates this figure to forty years, demonstrating that the T. rex it was growing much slower than we thought.
invisible rings. There are two problems related to calculating the age of fossils Tyrannosaurus rexand their growth rate, based on the traditional rings that form in the leg bones. The first is that the bones themselves do not hold a complete record of the animal’s growth, but only the last twenty years. The second problem is that, as the Oklahoma State University team that conducted the study discovered, there are “invisible” growth rings that we never considered in our analyses.
15 years older. Discovered and highlighted thanks to a new technique that uses polarized light to make them “appear”, these rings have led researchers to profoundly review the calculations on the growth rates of Tyrannosaurus rex. By analyzing 17 different specimens, of equally different ages, and “stitching together” the data, the team calculated that the T. rex they didn’t stop growing at 25, but continued to do so into their 40s.
This slower growth, according to the authors, allowed these dinosaurs to exploit different ecological niches throughout their lives, changing them in parallel with their growth in size.
Tyrannosaurs… or something else? In addition to revolutionizing the perception of how and how much children grow Tyrannosaurus rexthe study also puts forward another hypothesis. According to the authors, in fact, the growth rates of some of the most famous fossil specimens are incompatible with those of the study: this could mean that it was not a question of T. rex but of other species.
An example is the famous Nanotyrannuswhich until recently was classified as “juvenile specimens of T. rex” and which is now considered a separate genre. Jane and Petey, two of the most famous fossils of T. rex of the world, they could therefore be another species, and like them other specimens that have always been identified as tyrannosaurs but whose nature perhaps needs to be revised in the light of this new study.