PALEONTOLOGY SHOCK: Tylosaurus rex – Texas’s New “Sea Monster” Larger Than a Truck That Ruled the Ocean 80 Million Years Ago!

A colossal new mosasaur species has been formally named Tylosaurus rex (“king of the tylosaurs”), a 13-metre (43-foot) giant that prowled the Western Interior Seaway over what is now northern Texas 80 million years ago. One of the largest mosasaurs ever discovered, this apex predator boasted finely serrated teeth, reinforced skull adaptations for mᴀssive jaw muscles, and evidence of brutal intraspecific combat.

Described in May 2026 in the Bulletin of the American Museum of Natural History by Amelia Zietlow and colleagues from the American Museum of Natural History, Perot Museum of Nature and Science, and Southern Methodist University, the species was erected from long-misidentified fossils collected decades earlier. The holotype—a spectacular mounted skeleton at the Perot Museum in Dallas—was originally labelled Tylosaurus proriger. Re-examination revealed consistent differences: larger body size (7.7–13.2 m), serrated denтιтion rare among mosasaurs, and cranial features indicating a more powerful bite.

These Texas specimens are also 4 million years younger than classic T. proriger from Kansas, confirming a distinct species. Bite marks and healed injuries on several bones suggest fierce fights with rivals. Living in the shallow Campanian seas, T. rex hunted fish, sharks, turtles, and possibly other mosasaurs with terrifying efficiency.

The discovery proves that museum collections still harbour revolutionary finds and highlights Texas as a H๏τspot for giant tylosaurines. As Zietlow noted, this “T. rex of the sea” was every bit as formidable as its terrestrial namesake—proving everything really is bigger in Texas. The Perot Museum specimen is now a star attraction, bringing the ultimate Cretaceous sea monster back to life.