The discovery of a dinosaur’s braincase is always a precious thing in the fossil record. Braincases are important to paleontologists in helping to determine the acuity of dinosaurs' sensory arsenal. Enter Timurlengia euotica. It was described scientifically by well-known paleontologist and tyrannosaur expert Stephen Brusatte, with a team comprising Hans Dieter-Sues, Amy Muir, Ian Butler and Alexander Amerianov. The study, which was published in Proceedings of the National Academy of Sciences, has taken the world of paleontology by storm.
At first, the animal seemed to be just another typical early tyrannosaur in terms of its dimensions. It was about half a ton in weight, somewhat sizable by today’s standards but downright puny compared to its gigantic later relatives. Yet from the bones we have, which consist of skull bones and postcrania (remains from the body), we can see that this predator may have been quite similar to its later descendants. It had the famously small but muscular arms and two-fingered hands of later tyrannosaurs as well as the possibly large and strong skull that made them such celebrities in the dinosaur world. In short, it was setting the physical blueprint for the giant predators of the future. The monstrous likes of Tarbosaurus, Albertosaurus and T. rex would owe their body plan entirely to Timurlengia and its line of animals in what is known as the “head-first” model of tyrannosaur evolution.
According to Brusatte and colleagues, this is among the few good tyrannosaurs from the middle of the Cretaceous. There is a large blank spot during this time, around 90 million years ago, a supposed transitional period when these creatures began to grow more like their later descendants. Many primitive genera held lower niches in the ecosystem, surviving as jackal-like hunters while only a few side branches of the family emerged as top predators where they lived. Studies of Timurlengia show us that the characteristic huge heads of the most advanced tyrannosaurs evolved before their massive size could, an interesting revelation for many paleontologists.