Paleontologists have long hailed Tyrannosaurus rex as king of the dinosaurs. Now, the name “T. rex” also belongs to a newly described extinct carnivore — a massive marine reptile with the scientific name Tylosaurus rex that a trio of researchers uncovered after a hefty amount of detective work.
The freshly crowned T. rex wasn’t a dinosaur but a mosasaur, a gigantic ocean apex predator that lived about 80 million years ago — a bit earlier than the dinosaur king, which lived 68 million to 66 million years ago — and measured up to 43 feet (13 meters) long. The sleuthing scientists identified the species from fossils attributed for decades to a closely related mosasaur.
Like the land-dwelling T. rex (rex means king in Latin), the huge creature ruled its habitat, its sawlike teeth tearing into its prey — fish, turtles and long-necked marine reptiles called plesiosaurs — “really crunching through and ripping them up,” said Amelia Zietlow, a paleontologist with the History Museum at the Castle in Appleton, Wisconsin. Zietlow is lead author of a new study describing Tylosaurus rex, published May 21 in the journal Bulletin of the American Museum of Natural History.
Fossils of the long-snouted swimmer were found in what’s now Texas and date back about 80 million years to the latter part of the Cretaceous Period, a time when an inland sea partly covered the North American continent. For the new study, Zietlow and her coauthors examined and reclassified fossils housed in more than a dozen institutions — specimens that had been misidentified as the species Tylosaurus proriger.
“Here we have two T. rexes, one the king of the dinosaurs on land, the other the king of the reptiles in the water, both about the same size, 40 feet long or so, and both dominant at the top of the food chain, as the biggest carnivores in their ecosystems,” said paleontologist Steve Brusatte, a professor of paleontology and evolution at Scotland’s University of Edinburgh, in an email. Brusatte was not involved in the research.
The discovery serves as a reminder that scientific breakthroughs can come from museum collections as well as newfound fossils, and that amateur dinosaur enthusiasts also can play an important part in identifying species new to science, Zietlow noted.
“A lot of these specimens were dug up and donated by avocational or hobbyist paleontologists in the Dallas area, so there was a lot of community involvement,” she said. “This is a really great case of what paleontology can be, if everyone works together.”
