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Long before humans existed, giant marine predators ruled the warm prehistoric seas that once covered much of North America. Among them was a newly identified species called Tylosaurus rex, a massive mosasaur that stretched nearly 43 feet in length and lived more than 80 million years ago. Armed with serrated teeth, powerful jaws and strong neck muscles, the enormous reptile may have been one of the most formidable hunters of the Late Cretaceous period. Scientists identified the species after re-examining fossils discovered in northern Texas that had previously been assigned to another tylosaur species. Researchers say the findings suggest the predator displayed unusually aggressive behaviour compared with previously known tylosaurs. The study was published in the Bulletin of the American Museum of Natural History.
What made the 43-foot ‘marine T rex’ such a dangerous predator
Despite the dramatic nickname, Tylosaurus rex was not closely related to Tyrannosaurus rex. Tyrannosaurus rex was a land-dwelling dinosaur, while Tylosaurus rex belonged to a separate group of giant marine reptiles known as mosasaurs.Researchers say the comparison mainly reflects the animal’s enormous size and fearsome predatory behaviour. The name Tylosaurus rex roughly translates to “king of the tylosaurs”.Scientists also say the species may have been more aggressive than previously known tylosaurs. Study author Ron Tykoski described the creature as appearing “meaner” than related mosasaurs due to fossil evidence suggesting unusually violent injuries.Researchers began suspecting the fossils represented a different species after identifying unusual features not typically seen in other tylosaurs.One of the most important clues involved the teeth. Unlike many other mosasaurs, Tylosaurus rex possessed finely serrated teeth adapted for slicing flesh. Researchers also found that the fossils were about four million years younger than the species they had originally been assigned to, helping confirm they belonged to a separate species.Scientists say the reptile also had exceptionally strong jaw and neck muscles, suggesting it was capable of overpowering large prey in prehistoric oceans.
Fossils showed signs of violent injuries
One fossil specimen nicknamed “The Black Knight”, housed at the Perot Museum of Nature and Science, provided some of the most dramatic evidence.The fossil is missing part of its snout and contains a fractured lower jaw. Researchers believe the injuries were likely inflicted by another Tylosaurus rex during violent interactions between members of the species.Scientists say this level of apparent aggression has rarely been documented in tylosaur fossils before. The injuries suggest the animals may have fought over territory, food or mating opportunities.
The ancient sea that covered Texas
More than 80 million years ago, much of central North America was submerged beneath a massive inland sea known as the Western Interior Seaway.The warm prehistoric ocean stretched from the Gulf of Mexico to the Arctic Ocean and supported a rich ecosystem filled with giant marine predators. Tylosaurus rex would have shared these waters with ancient sharks, plesiosaurs, sea turtles, ammonites and other mosasaurs.Mosasaurs were among the dominant marine predators of the Late Cretaceous period and occupied the top levels of prehistoric ocean food chains.Researchers say the discovery could reshape scientific understanding of mosasaur evolution. For decades, many studies relied on older fossil classification systems that grouped several similar species together. Scientists have now assembled a revised fossil dataset that may reorganise the tylosaur family tree.Co-author Amelia Zietlow said the findings highlight the need to revisit long-standing assumptions about mosasaur evolution and modernise the methods used to study ancient marine reptiles.Another study author, Michael Polcyn said Texas remains one of the world’s most important regions for understanding prehistoric marine ecosystems.
Not technically a dinosaur
Although many headlines describe Tylosaurus rex as a “marine dinosaur”, mosasaurs were technically marine reptiles rather than true dinosaurs.Mosasaurs were part of the squamate lineage that also includes modern monitor lizards and snakes, although they were not direct ancestors of either group. They evolved streamlined bodies, paddle-like limbs and powerful tails that made them highly effective ocean hunters.Mosasaurs eventually disappeared during the same mass extinction event that wiped out non-avian dinosaurs around 66 million years ago.For palaeontologists, Tylosaurus rex represents more than just another giant predator. The species may provide important new insights into how massive marine reptiles evolved, competed and dominated Earth’s ancient oceans millions of years before humans existed. Go to Source
