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.
Bagaceratops
Bagaceratops, meaning "small-horned face" (Mongolian "Baga" = "small"; Greek "ceratops" = "horn face"), is a genus of ceratopsian dinosaur that lived in what is now Mongolia around 80 million years ago, during the Late Cretaceous. Although emerging late in the reign of the dinosaurs, "Bagaceratops" had a fairly primitive anatomy and kept the small body size that characterized early ceratopsians.