Tyrannosaurus Mcraeensis: Is it time to rethink the apex predator?

Cover Image Credit: Sergey Krasovskiy

A team of researchers, including University of Bath academics, have identified a new species of dinosaur known as Tyrannosaurus mcraeensis. The study published in Scientific Reports on January 11th 2024, sheds light on the previously unknown relative of the T. Rex, using the remains of a skull unearthed in western New Mexico The skull was pieced together bone by bone, showing clear divergence from the classic T. Rex skull. The result is a species of dinosaur roughly the same size as a T. Rex but predating it by 72 million years (Dalman et al., 2024). The tyrannosaurus rex is a widely known and loved dinosaur as well as possibly one of the most studied, with more than 120 specimens identified. Although there is still much more to discover. The tyrannosaurus rex was believed to have appeared around 66 million years ago in western North America, except for being one of the largest terrestrial carnivores; it is hard to believe they can appear out of nowhere. Extensive studies have been carried out in this area to no avail; however, there may finally be a break.

The tyrannosaurus mcraeensis predates the T. Rex by 72 million years, and further study reveals subtle jaw differences between the two species. This evidence suggests that the two dinosaurs are not directly related and that plenty more species of tyrannosaur are yet to be discovered.

The evolutionary history of the T. Rex may finally be uncovered. Additionally, the dinosaur was discovered in western New Mexico, while the T. Rex is believed to have inhabited western North America and eventually worked its way further north. It now seems the gigantism of the tyrannosaurs occurred in southern North America, unlike its distant relatives in Asia. While mammal evolution patterns show increasing size in northern parts of continents, tyrannosaurs have done the opposite. As it evolves, it appears to make its way western until suddenly expanding north along with horned dinosaurs, possibly because of the suitable food source.

So, what does this all mean? The tyrannosaurus mcraeensis was previously misidentified by scientists as another T. Rex fossil, meaning that many fossils currently identified as T. Rex may actually be other species of dinosaurs, some possibly undiscovered (Longrich, 2024). This underlines the issue of accurate identification within palaeontology and the need for further study within the field. Southern North America has also been highlighted as an epicentre for evolution within tyrannosaurs, with a diverse range of larger dinosaurs evolving in that region. This unleashes an expansive range of questions about what factors drove this evolutionary change and how it may have been related to the climate.

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