Tylosaurus proriger (Cope, 1869) lived in the Late Cretaceous Western Interior Seaway, which covered the middle of the United States, from the Rocky Mountains to the Appalachians. It was 46’ long (possibly as long as 50'!) and weighed around 6 tons, making it the longest, and amongst the heaviest, of all marine reptiles and the king of the mosasaurs, a group of sea-going reptiles known for their large, toothy skulls and long bodies. Its closest living relative is the Komodo dragon!
Tylosaurus's propulsion comes via a long, deep tail. Consisting of over 80 individual bones, each of which provided a huge surface area for massive muscles, Tylosaurus was capable of tremendous bursts of speed. Its paddle-limbs were used for steering rather than for forward motion.
Numerous nearly complete specimens have been discovered, especially in the chalks of Kansas. It wasn't a picky eater as stomach contents including mosasaurs, plesiosaurs, sharks, fish, and even birds have been recovered from skeletons.
Tylosaurus had ~72 teeth in its huge mouth (you can purchase one here). In addition to the usual top and bottom teeth, it had 2 rows of teeth in the roof of its mouth, called pterygoid or palatal teeth which helped impale and hold slippery prey. Its teeth all curve strongly towards the back of the mouth and its jaws had mobility allowing it to "walk" an animal down its throat by moving parts of its jaw similar to a snake.
Tylosaurus lacked teeth in the front of its mouth, thus the reason for being named the "protuberance lizard". It may have used its bottle-like snout as a battering ram, either to stun prey to fight with other Tylosaurus for territory and mating purposes.
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