By examining the annual markings on the bones, the scientists determined the average age of nanotyrannosaurs to be 13-15 years, which is the same age as young tyrannosaurs. But the marks are arranged very densely, the difference in bone growth between years is symbolic, indicating that the creature is approaching its maximum size, its maturation. Young Tyrannosaurus grew quickly and added a hundred kilograms of weight per year, but in this case the picture is different.
Finally, no transitional “adolescent” forms have been found that combine features of the two species, which indicates their difference. A direct comparison of the skulls of a young Tyrannosaurus and Nanotyrannosaurus showed how different they are. The former would have been a powerful and clumsy predator, while the latter was already an agile and nimble hunter. The study is still far from complete, scientists do not rule out new discoveries.
