Macrurosaurus, which translates to "large-tailed lizard," is the designated name for a dinosaur genus that thrived during the Early Cretaceous. This titanosauriform roamed the lands that now constitute England. The type species, M. semnus, was officially identified in 1876.

A notable challenge associated with the Macrurosaurus genus lies in the fact that it is exclusively represented by two isolated sets of caudal vertebrae, discovered separately and subsequently joined together. This, coupled with the absence of any other fossilized remains attributed to the genus, leads certain paleontologists to question the validity of the genus, as it becomes exceptionally challenging to definitively link additional remains to Macrurosaurus. Interestingly, Seeley himself estimated Macrurosaurus to be approximately twelve meters in length.