Full Breakdown
Texas's New “Sea T. rex”: A Giant Mosasaur Redefined
5/22/2026, 11:29:34 AM
New Species Identified
A team from the American Museum of Natural History, the Perot Museum of Nature and Science, and Southern Methodist University described *Tylosaurus rex* from ~80 Ma marine deposits in north-central Texas. The holotype, found near Lake Ray Hubbard, reaches 43 ft (13 m), about twice the length of a great-white shark. The name means “king of the tylosaurs” and separates it from the earlier *T. proriger*.
Reevaluation of Misidentified Fossils
The holotype had been catalogued as *T. proriger*. Comparison with Harvard’s type specimen revealed serrated teeth, a longer skull, and a sturdier jaw. Surveying collections uncovered >12 similar fossils, leading to the reassignment of specimens such as “Bunker” (University of Kansas) and “Sophie” (Yale Peabody Museum) to *T. rex*.
Anatomy and Intraspecific Combat
- T. rex* had massive jaw and neck muscles, evident from large attachment sites on the skull and vertebrae. The “Black Knight” specimen lacks its snout tip and shows a fractured lower jaw, injuries likely caused by another individual. Similar trauma on “Sophie” indicates frequent aggressive encounters.
Implications and Future Research
The team introduced a revised character matrix for mosasaur phylogenetics, arguing that the long-used dataset is outdated. Adding *T. rex* data reshapes the tylosaur family tree and suggests more intricate relationships within Mosasauridae. Zietlow said the discovery calls for revisiting long-standing assumptions about mosasaur evolution and updating analytical tools. Tykoski noted that the observed intraspecific injuries are more severe than those recorded in other Tylosaurus species. Polcyn emphasized that the findings highlight Texas’s importance for reconstructing ancient marine ecosystems. The researchers plan to enlarge the dataset with more North Texas fossils and apply modern computational analyses to test alternative evolutionary scenarios, with citizen scientists aiding field collection.
Verbatim Quotes
- “Everything is bigger in Texas and that includes the mosasaurs, apparently,” — Amelia Zietlow, research associate, American Museum of Natural History
- “Through our study and examination of well-preserved fossils collected throughout the north Texas region, we have evidence of violence within this species to a degree not previously seen in other Tylosaurus specimens.” — Ron Tykoski, vice president of science, Perot Museum of Nature and Science
- “It highlights the need to revisit long-standing assumptions about mosasaur evolution and to modernize the tools we use to study these iconic marine reptiles.” — Amelia Zietlow, co-author
- “These findings reshape both the physical and evolutionary picture of mosasaurs, underscoring Texas as a key region for understanding ancient marine ecosystems and signalling a new era of research into the evolutionary history of these formidable predators,” — Michael Polcyn, SMU paleontologist
