Fossil Enchodus tooth, Saber tooth salmon. Super cool tooth for sale.
Although they weren’t technically dinosaurs, mosasaurs hold a unique place in paleontological history: it was the discovery of a specimen of Mosasaurus in 1764, in a Dutch quarry that galvanized scientists into the realization that species could become extinct (and that the earth used to be populated by some very strange creatures). Mosasaurus (“lizard from the Meuse River”) was soon named by the renowned naturalist Georges Cuvier, and the general name “mosasaur” attached to other members of this ancient family. In evolutionary terms, mosasaurs were distinct from three other famous groups of marine reptiles, ichthyosaurs (“fish lizards”), long-necked plesiosaurs, and short-necked pliosaurs.
These sleek, reptilian predators may have been responsible for the extinction of the ichthyosaurs by the end of the Cretaceous period (not necessarily by eating them, but by out-competing them for food), and their quick, agile, hydrodynamic builds gave plesiosaurs and pliosaurs a run for their money. Essentially, mosasaurs ruled the seas for about 20 million years, until the K/T Extinction expunged most giant reptiles from the face of the earth 65 million years ago.
While it would be tempting to speculate that mosasaurs evolved from ichthyosaurs and plesiosaurs, this doesn’t appear to be the case. The recent discovery of the small, amphibious Dallasaurus, which was capable of swimming as well as walking on land, hints that mosasaurs evolved from early Cretaceous reptiles very similar in appearance to modern monitor lizards.
