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.
Gasosaurus
"Gasosarurus" lived during the mid-Jurassic period (Bathonian and/ or Callovian stages), around 164 million years ago. It coexisted with other mid-range theropods such as "Chuandongocoelurus" and "Kaijiangosaurus", two other dinosaurs found from the Lower Shaximiao Formation. These three taxa pertain to medium to large bodied theropods and are known from associated prostcranial skeletons. China, boasts the highest taxic diversity of Middle Jurassic theropods of all body sizes from anywhere in the world. Most Middle Jurassic theropods from china are 'medium-sized', as are the majority of Middle Jurassic theropods globally.