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.
East Windsor, Connecticut
In 1818, resident Solomon Ellsworth Jr, was blasting a hole for his well to go alongside of his house in town. While in the process, he found some foreign bones, not known at the time. These bones would last be sent to Yale University and would later determine to be Dinosaur fossils, specifically, one of a Anchisaurus. Though not the first fossils to be found, the discovery of the fossils led to the dinosaur discovery craze that occurred later on in the century as these were the first bones to be known as a dinosaur, four years before William Buckland determined it. The bones are still at Yale while the Ellsworth Homestead still stands on Rye Street near the South Windsor line.