Scientists have found a huge bone from a possible ancestor of T. rex

The results of the study are published in the journal Scientific Reports.

The bone was found in New Mexico in the Kirtland Formation, a famous excavation site where dinosaur remains are often found.

We are talking about the tibia (shin bone), which is almost one metre long. Scientists estimate that the dinosaur to which it belonged could weigh between 4 and almost 6 tonnes.

This makes it one of the larger members of the Tyrannosauridae family, which lived long before the famous T. rex.

Details

To determine the dinosaur's place on the evolutionary tree, the researchers compared the bone they found with data on 537 anatomical features of other tyrannosaurs.

The analysis showed that this dinosaur was likely a close relative of Tyrannosaurus' ancestors.

Why it's important

The discovery may support the hypothesis that giant tyrannosaurs first appeared in southern North America and then spread further north.

About 74 million years ago, this region was a separate continent, Laramidia, where different dinosaur species evolved independently of each other.

If the hypothesis is confirmed, it will help scientists better understand the origin of the most famous predatory dinosaurs on Earth.

Background

Tyrannosaurus rex lived much later - about 66-68 million years ago, shortly before the mass extinction of dinosaurs.

Finds of older relatives may therefore reveal the early history of this group of predators.

Source

Nicholas R. Longrich et al, Scientific Reports (2026), DOI: 10.1038/s41598-026-38600-w