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.
Johann Leonard Hoffmann
Johann Leonard Hoffmann (1710–1782) was a Maastricht army surgeon and amateur geologist who collected fossils from the local Mount Saint Peter. He is known for fossils named after him, and was one of the three people contacted on the discovery of the Mosasaurus in 1766, and especially the second one in the 1770s known as "le grand animal", that was later taken to Paris by Napoleon's army in 1794.