Tylosaurus fossil map
Where fossils of Tylosaurus have been found, shown on the Earth as it looked about 75 million years ago and on today’s map.
Dots are fossil collections recorded in the Paleobiology Database. The “then” view moves today’s fossil sites back to their positions 75 million years ago (the time slice nearest the median age of the fossils) using the Merdith et al. (2021) plate model; positions are approximate. Open on the timeline map →
| Group | Mosasaurs |
|---|---|
| Lived | 93.9–66 million years ago (Turonian to Maastrichtian) |
| Periods | Cretaceous |
| Family | Mosasauridae |
| Named by | Marsh 1872 |
| Fossil records | 67 occurrences at 55 locations (PBDB) |
| Found in | United States, Sweden, Canada, Angola, Belgium, Germany, Spain, Mexico, Jordan, France |
| Rock formations | Niobrara, txn:38049, Pierre Shale, Tar Heel, Itombe, Boquillas |
About Tylosaurus
Tylosaurus (; "knob lizard") is a genus of russellosaurine mosasaur (an extinct group of predatory marine lizards) that lived about 92 to 66 million years ago during the Turonian to Maastrichtian stages of the Late Cretaceous. The genus contains at least ten validly named species, the largest of which, T. rex, estimated to have reached over 13 meters (43 ft) long and weighed nearly 8.4 tonnes (19,000 lb). Its fossils have been found primarily around North Atlantic Ocean including in North America, Europe, and Africa.
The first named species, T. proriger, was originally described in 1869 by Edward Drinker Cope as a member of a separate mosasaur genus, Macrosaurus which is now synonymous with Halisaurus, and subsequently redescribed as the type species of the genus Tylosaurus named in 1872 by Othniel Charles Marsh. Fossil evidence shows that Tylosaurus regularly engaged in intraspecific combat and consumed various prey as an apex predator of their ecosystem, including predatory fish, ornithuran birds, sea turtles, plesiosaurs and other mosasaurs. It had an endothermic metabolism, which is unlike nearly all modern squamates.
Text in “About” is quoted from the Wikipedia article Tylosaurus (revision 1379455173), licensed under CC BY-SA 4.0; introduction excerpted verbatim, formatting removed. Ages, family, authority and fossil records: Paleobiology Database, accessed 22 October 2026. Ages are those of the rock layers the fossils were found in.
