The 43-foot-long ‘Ocean Tyrannosaurus Rex’ was bigger than a great white shark and more ferocious than any mosasaur found in Texas

Long before humans came on the scene, giant ocean predators dominated the warm prehistoric oceans that once covered much of North America. Among them is a newly discovered species called Tyrannosaurus rex, a giant mosasaur that was nearly 43 feet long and lived 80 million years ago. With serrated teeth, powerful jaws and strong neck muscles, this giant reptile may have been one of the most powerful hunters of the late Cretaceous. Scientists identified the species after re-examining fossils found in north Texas that had previously been assigned to another T. rex species. The researchers say the findings suggest the predator displayed unusually aggressive behavior compared with previously known Tyrannosaurus rex. The study was published in the Bulletin of the American Museum of Natural History.

What makes 43 feet ‘Ocean Tyrannosaurus Rex‘Such a dangerous predator

Despite its dramatic nickname, Tyrannosaurus rex is not closely related to Tyrannosaurus rex. Tyrannosaurus rex was a land-dwelling dinosaur, while Tyrannosaurus rex belonged to another group of giant marine reptiles, the mosasaurs.Researchers say the comparison largely reflects the animal’s massive size and fearsome predatory behavior. The name Tyrannosaurus rex roughly translates to “King of the Tyrannosaurus Rex.”Scientists also say the species may have been more aggressive than previously known Tyrannosaurus rex. Study author Ron Tykoski described the creature as “meaner” than related mosasaurs because fossil evidence suggests the creature was subjected to unusually violent injuries.After discovering unusual features not seen in other Tyrannosaurus rex, researchers began to suspect that the fossils represented a different species.One of the most important clues involves teeth. Unlike many other mosasaurs, Tyrannosaurus rex had finely serrated teeth suitable for cutting meat. The researchers also found that the fossils were about four million years younger than the species they were originally assigned to, which helped confirm they belonged to a separate species.The reptile also had unusually strong jaw and neck muscles, suggesting it was capable of subduing large prey in prehistoric oceans, scientists say.

Fossils show signs of violent injury

A fossil specimen nicknamed “The Black Knight” in the collection of the Perot Museum of Nature and Science provides some of the most striking evidence.The fossil is missing part of its snout and has a broken jaw. Researchers believe the injuries were likely inflicted by another T. rex during a violent interaction between members of the species.Such overt aggression has rarely been recorded in Tyrosaurus fossils before, scientists say. These injuries indicate that the animals may be fighting over territory, food, or mating opportunities.

The ancient ocean that covered Texas

Eighty million years ago, much of central North America was submerged beneath a vast inland sea known as the Western Interior Seaway.Warm prehistoric oceans stretched from the Gulf of Mexico to the Arctic Ocean, supporting a rich ecosystem filled with giant marine predators. Tyrannosaurus rex likely shared these waters with ancient sharks, plesiosaurs, turtles, ammonites, and other mosasaurs.Mosasaurs were one of the major marine predators of the late Cretaceous, occupying the top of the prehistoric marine food chain.Researchers say the discovery could reshape scientific understanding of mosasaurs’ evolution. For decades, many studies relied on old fossil classification systems that grouped several similar species together. Scientists have now assembled a revised fossil data set that may reorganize the Tyrannosaurus rex family tree.Co-author Amelia Zietlow said the findings highlight the need to reexamine long-standing hypotheses about mosasaurs’ evolution and modernize methods for studying ancient marine reptiles.Michael Polcyn, another study author, said Texas remains one of the most important places in the world for understanding prehistoric marine ecosystems.

Not technically a dinosaur

Although many headlines describe Tyrannosaurus rex as a “marine dinosaur,” mosasaurs are technically marine reptiles and not true dinosaurs.Mosasaurs are part of a lineage of squamates that also includes modern monitor lizards and snakes, although they are not direct ancestors of either group. They evolved streamlined bodies, paddle-like limbs and powerful tails, making them efficient ocean hunters.Mosasaurs eventually disappeared in the same mass extinction event that wiped out non-avian dinosaurs about 66 million years ago.To paleontologists, T. rex represents more than just another giant predator. The species may provide important new insights into how large marine reptiles evolved, competed and dominated Earth’s ancient oceans millions of years before humans existed.