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 Massachusetts
Paleontology in Massachusetts refers to paleontological research occurring within or conducted by people from the U.S. state of Massachusetts. The fossil record of Massachusetts is very similar to that of neighboring Connecticut. During the early part of the Paleozoic era, Massachusetts was covered by a warm shallow sea, where brachiopods and trilobites would come to live. No Carboniferous or Permian fossils are known from the state. During the Cretaceous period the area now occupied by the Elizabeth Islands and Martha's Vineyard were a coastal plain vegetated by flowers and pine trees at the edge of a shallow sea. No rocks are known of Paleogene or early Neogene age in the state, but during the Pleistocene evidence indicates that the state was subject to glacial activity and home to mastodons. The local fossil theropod footprints of Massachusetts may have been at least a partial inspiration for the Tuscarora legend of the Mosquito Monster or Great Mosquito in New York. Local fossils had already caught the attention of scientists by 1802 when dinosaur footprints were discovered in the state. Other notable discoveries include some of the first known fossil of primitive sauropodomorphs and "Podokesaurus". Dinosaur tracks are the Massachusetts state fossil.