Mosasaur
Mosasaurs (from Latin "Mosa" meaning the 'Meuse river', and Greek σαύρος "sauros" meaning 'lizard') are an extinct group of large marine reptiles containing 38 genera in total. Their first fossil remains were discovered in a limestone quarry at Maastricht on the Meuse in 1764. Mosasaurs probably evolved from an extinct group of aquatic lizards known as aigialosaurs in the Early Cretaceous. During the last 20 million years of the Cretaceous period (Turonian-Maastrichtian ages), with the extinction of the ichthyosaurs and pliosaurs, mosasaurs became the dominant marine predators. They became extinct as a result of the K-Pg event at the end of the Cretaceous period, about 66 million years ago.
Paleontology in Louisiana
Native peoples of Louisiana interpreted local mastodon fossils as the remains of monsters. They referred to the creatures as the grandfather of the buffalo. This subject was discussed in a 1748 letter from a French military officer named Fabri to Georges Cuvier. In 1804, such large fossil bones were discovered on land belonging to the Opelousa people. In 1816, the state's famous fossil site at Montgomery Landing was discussed in writing. It was not until 2004 that any dinosaur fossils were reported from Louisiana. The first such find was a single tooth reworked out of Cretaceous rocks and preserved in a Miocene-aged fossil deposit near Fort Polk. The dinosaur it came from probably lived, died, and was initially buried to the north in Arkansas. Later, it was eroded from Cretaceous sediments enclosing it and an ancestral Sabine River transported it southward to where it was found. The bones of Pleistocene megafauna, including mastodons, sometimes are found during the excavation of loess for fill or the construction of roads or buildings.The most famous fossil sites within Louisiana are Creola Bluff at Montgomery Landing Site in Grant Parish, Louisiana and the Cane River Site, Natchitoches Parish, Louisiana. The Montgomery Landing Site was a long and high bluff that was the cutbank on the east side of the Red River. It exposed the top of the Cockfield Formation, the Moodys Branch Formation, and Tullos Member of the Yazoo Clay. The Moodys Branch Formation and Yazoo Clay were extremely fossiliferous with over a 100 species of invertebrate fossils and numerous species of vertebrate fossils, including one of the finest Eocene whale skulls known to science, having been found at this fossil site. Unfortunately, channelization of and construction along Red River has resulted in lower portions of the site being covered by sediment and the remaining exposures being completely covered by colluvium and overgrown by vegetation. As a result, fossils can no longer be found at this site. The Cane River Site is a low road-side cut made doing the construction of Interstate Highway 49 near Natchitoches, Louisiana. It exposes several feet of 44.5 to 46.5 Ma glauconitic silty clay belonging to the Cane River Formation. About 150 different species of marine invertebrate and vertebrate fossil have been found at this site. This site is slowly being destroyed by weathering and overgrown by vegetation.