Megalodon is an extinct genus of bivalve molluscs that reportedly lived from the Devonian to the Jurassic Period. It is not clear, however, that all the fossils assigned to Megalodon from that span of time really belong in the same genus. Jurassic relatives of Megalodon such as Pachyrisma grande were closely related to the rudists. Megalodon is the only genus in the family Megalodontidae.

Megalodon is an extinct genus of bivalve molluscs that reportedly lived from the Devonian to the Jurassic Period. It is not clear, however, that all the fossils assigned to Megalodon from that span of time really belong in the same genus. Jurassic relatives of Megalodon such as Pachyrisma grande were closely related to the rudists. Megalodon is the only genus in the family Megalodontidae.