New T-Rex Species Identified in North America

A recent fossil discovery in New Mexico is shaking up everything we thought we knew about the most famous dinosaur in history. Paleontologists are actively debating whether a set of newly examined bones belongs to a distinct relative of the Tyrannosaurus rex. This potential new species could completely rewrite the timeline of apex predators in North America.

The Discovery of Tyrannosaurus mcraeensis

In early 2024, a team of paleontologists published a study proposing the existence of a brand-new species called Tyrannosaurus mcraeensis. The story of this discovery actually begins several decades ago. In 1983, a boater exploring the shores of Elephant Butte Reservoir in New Mexico noticed a piece of bone sticking out of the rock.

These fossils were excavated from the Hall Lake Formation and moved to the New Mexico Museum of Natural History and Science. For years, museum curators and scientists labeled the partial skull and jawbone as standard T. rex remains. It was not until a research team, including paleontologists Sebastian Dalman and Nick Longrich, took a closer look that they noticed strange inconsistencies. The bones did not perfectly match the famous predator we all know.

Subtly Different Anatomy

At first glance, Tyrannosaurus mcraeensis looked incredibly similar to a standard T. rex. It was a massive, bipedal carnivore that stretched roughly 40 feet long and weighed up to 8 tons. It had the same terrifying teeth and large head. However, the differences lie in the fine details of the skull.

The researchers pointed out that the lower jawbone, known as the dentary, is shallower and curves differently than that of a T. rex. Additionally, the new skull lacks the prominent, bumpy ridges right above the eyes that are a classic feature of the traditional Tyrannosaurus rex. While these differences might sound minor to a casual observer, in the world of paleontology, structural shifts in a jawbone often indicate a completely different diet, bite force, or evolutionary branch.

The Seven-Million-Year Gap

The most compelling argument for this being a new species is not just the shape of the bones, but the age of the rocks they were found in. Tyrannosaurus rex is famous for living at the very end of the Late Cretaceous period, right before the asteroid impact. T. rex fossils consistently date back to between 66 and 68 million years ago.

The rocks of the Hall Lake Formation tell a different story. Geological dating places the Tyrannosaurus mcraeensis fossils at roughly 71 to 73 million years old. This creates a massive five-to-seven-million-year gap between this New Mexico dinosaur and the classic T. rex. If the dating is accurate, it means giant tyrannosaurs were hunting in North America millions of years earlier than scientists previously believed.

The Paleontology Debate: Is It Really a New Species?

Science requires rigorous proof, and the announcement of a new Tyrannosaurus species immediately sparked a healthy debate among experts. Not everyone is convinced that Tyrannosaurus mcraeensis deserves its own distinct category.

Paleontologists like Thomas Carr, who specializes in tyrannosaur growth and evolution, remain highly skeptical. The counterargument centers on the idea of individual variation. Just as human faces come in different shapes and sizes, dinosaurs had natural variations in their bone structures. A shallower jaw or a missing ridge could simply be a quirk of that specific animal.

Skeptics also point out that dinosaur bones change dramatically as the animal ages from a juvenile to a full-grown adult. Differences in skull shape can also occur between males and females of the exact same species. Because the New Mexico fossils are fragmented and incomplete, some experts argue there is simply not enough physical evidence to declare it a completely new relative. They suggest it might just be an oddly shaped, or perhaps early, T. rex.

Shifting the Dinosaur Origin Story

If Tyrannosaurus mcraeensis is universally accepted as a new species, it solves a long-standing mystery regarding where these giant predators came from.

During the Late Cretaceous period, North America was divided in half by a massive inland sea. The western half formed an island continent called Laramidia. Most T. rex fossils are found in the northern parts of Laramidia, in places like modern-day Montana, Wyoming, and the Dakotas. Because of this, scientists largely assumed T. rex evolved in the north or migrated from Asia over a land bridge.

Finding a massive, older relative in New Mexico flips this theory upside down. It suggests that the giant tyrannosaur lineage actually originated in the southern part of North America. According to this new theory, these predators evolved to massive sizes in the south to hunt giant horned dinosaurs and giant duck-billed dinosaurs. Only millions of years later did they migrate north to become the iconic T. rex that dominated the end of the dinosaur age.

Frequently Asked Questions

What is the name of the newly proposed T-rex relative? The newly identified species is named Tyrannosaurus mcraeensis. It is named after the McRae Group, the specific series of rock layers in New Mexico where the fossils were originally discovered.

Where were the Tyrannosaurus mcraeensis fossils found? The fossils were found near Elephant Butte Reservoir in southern New Mexico. They are currently housed at the New Mexico Museum of Natural History and Science in Albuquerque.

How much older is this new species than the T. rex? Geologists estimate that Tyrannosaurus mcraeensis lived roughly 71 to 73 million years ago. This makes it roughly 5 to 7 million years older than the traditional Tyrannosaurus rex, which lived 66 to 68 million years ago.

Why do some scientists disagree about the discovery? Many paleontologists believe the differences in the skull are too minor to justify a whole new species. They argue the variations in the jawbone could just be individual differences, related to the dinosaur’s age, or due to natural variations between males and females of the standard T. rex species.