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.
Nyctosauridae
Most nyctosaurid fossils have been found in formations dating to the late Cretaceous period of the western United States and Mexico. "Nyctosaurus" dates from 85-84.5 million years ago, in the Niobrara Formation of Kansas. "Muzquizopteryx" is the oldest nyctosaurid known from definitive remains, dating to the Turonian-Coniacian boundary, 85.8 million years ago, in Coahuila. However, a partial humerus with the distinctive nyctosaurid deltopectoral crest was found in Cornet, Romania, and identified as a possible European, early Cretaceous (late Berriasian age, about 140Ma ago) nyctosaurid by Gareth Dyke and colleagues in 2010.