In a page ripped out of Michael Crichton’s book Jurassic Park, featuring brilliant mathematician and “chaotician” (chaos theory specialist) Ian Malcom, three scientists applied a new statistical approach to combine analyses from 17 different T. rex specimens, thus revealing that these tyrant lizard kings did not reach maturity until age 40.* Enjoy some fearsome pictures of T. rex’s big and small in this press release from Oklahoma State University citing lead author Dr. Holly Woodward, professor of anatomy and paleontology.

Dr. Woodward says that previous studies estimated that T. rex growth stopped around age 25. The longer development time expands the role of knife-teethed, fleet-footed juvenile T. rex’s to dominate the mid-carnivore niche.

A four-decade growth phase may have allowed younger tyrannosaurs to fill a variety of ecological roles within their environments. That could be one factor that allowed them to dominate the end of the Cretaceous Period as apex carnivores.

– Coauthor Jack Horner, technical advisor for the Jurassic Park films (inspiring the Alan Grant character)

Sensational!

* Prolonged growth and extended subadult development in the Tyrannosaurus rex species complex revealed by expanded histological sampling and statistical modeling, Woodward, Myhrvold and Horner, January 14, 2026