Megalodon is an extinct genus of bivalvemolluscs that reportedly lived from the Devonian to the Jurassic period.[1] 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.[2]
^ abc"Megalodon". The Paleobiology Database. Retrieved 2009-10-29.
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Skelton, Peter W. & Smith, Andrew B. (2000). "Preliminary phylogeny for rudist bivalves: sifting clades from grades". In Harper, E. M.; Taylor, J. D. & Crame, J. A. (eds.). Evolutionary Biology of the Bivalvia. Vol. Special Publication No. 177. Bath, UK: Geological Society. pp. 97–127. ISBN1-86239-076-2.