Tyrannosaurus rex may have taken significantly longer to mature than scientists once believed. A study of 17 tyrannosaur fossils indicates the apex predator required roughly 40 years to attain its full size of about eight tons.
The finding pushes back prior growth estimates by 15 years, reshaping understanding of dinosaur life history. Researchers suggest the slow growth rate may reflect a distinct metabolic strategy or environmental pressures not seen in other large theropods.
Data come from fossilized leg bones and growth rings, which act much like tree rings. The analysis provides the most detailed timeline yet for T. rex maturation, though the sample size remains small.
The extended growth period implies T. rex juveniles were vulnerable to predators and competition for longer than assumed. It also raises questions about how such slow-growing animals dominated their ecosystems.
The study's authors caution that 17 fossils represent a limited dataset, and individual variation could be significant. More specimens are needed to confirm the pattern across the species.