Overview
- The paper published Monday in the Bulletin of the American Museum of Natural History formally names Tylosaurus rex and estimates the animal at about 13.2 metres (43 feet) long with finely serrated teeth.
- The discovery began when Dr. Amelia Zietlow re‑examined a mislabeled American Museum of Natural History specimen and, after comparing material across North American collections, concluded the fossils represented a distinct species.
- More than a dozen specimens long assigned to Tylosaurus proriger have been reassigned to T. rex, including the Perot Museum’s holotype nicknamed the Black Knight and well‑known displays such as Bunker and Sophie.
- Fossils assigned to T. rex are concentrated in present‑day Texas and appear roughly four million years younger than classic Kansas T. proriger material, suggesting separate populations or species through time and space.
- Authors present a revised character dataset and call for wider museum relabeling, renewed fieldwork, and fresh phylogenetic analyses, which will require curators to update labels and could change how mosasaur evolution is interpreted.