Mamenchisaurus is a genus of sauropod dinosaurs that lived during the Late Jurassic period. It had a long neck that made up more than half of its total body length. However, there are several other names that have been used to describe this dinosaur. Some of the synonyms for Mamenchisaurus include Chialingosaurus, Omeisaurus, and Tienshanosaurus, to name a few. These names were used for different species within the same family and have slightly different characteristics. Despite the varying names, all of these dinosaurs were massive herbivores that roamed the ancient Earth millions of years ago and continue to fascinate scientists and dinosaur enthusiasts today.