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, measuring over 13 meters (43 ft). 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.

Research history

Possible first finds

The earliest Tylosaurus fossils were likely discovered by various Native American peoples and may have been the source of much of their folklore, with the earliest known ones dating back to well before the arrival of European settlers, around the 1500s. More recent accounts from peoples living in the Great Plains even speak of an ancient era ruled by massive aquatic creatures that were in constant combat with thunderbirds and were petrified by them. The considerable presence of fossils of large mosasaurs such as Tylosaurus and pterosaurs such as Pteranodon in this region may have been the origins of these myths.

In 1804, the Lewis and Clark Expedition discovered a now-lost fossil skeleton alongside the Missouri River, which was identified as a 45-foot (14 m) long fish.