“Jane and Petey were growing pretty quickly up until they died.”The researchers then looked at the bones’ cyclical growth marks. (For example, the cyclical growth marks in the bones of Svalbard reindeer correspond with polar winters, when the food supply is lowest.) By counting these growth marks, the researchers found that Jane died at around 13 years old, while Petey was around 15. For Jane and Petey, some of the rings are very close together, marking a year of minimal growth. The uneven spacing of the growth rings suggests that young T. rexes responded to the amount of resources available, growing quickly when food was plentiful, and stopping growth altogether when times were lean.

Source: New York Times January 03, 2020 19:07 UTC