By the age of 30, these reptiles had already accomplished everything in their lives.
According to a new study, Tyrannosaurus rex lived longer and reached its maximum size over a longer period than previously thought. This was reported on CNN's website.
It is noted that scientists had long counted the annual growth rings in the fossilized leg bones of Tyrannosaurus rex to determine both its age at death and its growth rate to adult size. Research showed that these dinosaurs typically stopped growing around the age of 25 and lived up to 30 years.
However, a new study published in the journal PeerJ details how a group of scientists used polarized light to detect previously invisible annual growth rings in 17 individual specimens. The analysis revealed that Tyrannosaurus rex would have reached its maximum size of about 8 tons only at the age of 35-40 years.
Unlike tree rings, the annual rings of dinosaurs reflect only the last 10-20 years of an individual's life. Interestingly, relying on the largest dataset ever collected on Tyrannosaurus, researchers were able to reconstruct its growth history year by year and found that dinosaurs grew much more slowly than previously thought. The lead author of the study, Holly Woodward, a professor of anatomy at Oklahoma State University, stated:
"Instead of rapid growth, Tyrannosaurus spent most of its life in an average body size range, rather than quickly reaching an overall length of 12 meters. Additionally, we found that the distance between annual rings varied among different individuals: some years showed significant growth, while others showed very little. This variability suggests that growth was flexible and likely depended on resource availability and possibly environmental conditions."
According to her, the study's results help scientists better understand the role of the king of dinosaurs in the world tens of millions of years ago.
"I think the study helps to understand why Tyrannosaurus was so successful as an apex predator - by developing slowly over a long period of time, Tyrannosaurus occupied many ecological niches throughout its life, ultimately becoming large enough to compete for resources only with other Tyrannosaurs," she said.
Annual Rings in Tyrannosaurus Fossils
It is also important that the differences in the growth curves of some specimens involved in the study intensify the scientific debate on whether what paleontologists considered a single species named Tyrannosaurus is actually a complex that includes other species or subspecies.
A recently published study found evidence that a specimen thought to belong to a juvenile Tyrannosaurus actually belonged to another species known as Nanotyrannus.
"Although the growth rates studied in this research cannot definitively prove the existence of separate species, the data obtained point to this intriguing possibility, among other possible explanations," the scientists stated.
