Megachasma and Orodus

Orodus greggi (Agassiz 1838, Late Pennsylvanian to Early Permian 300mya, 2m long) is basal hypbodontid shark close to Megaxhasma (below). The mandible is massive. The cranium is narrow. The fins are larger than illustrated by Zangrel 1981. The FMNH specimen preserves skin and gill slits.

Megachasma pelagios (Taylor, Compagno and Struhsaker 1983; up to 5m) is the extant megamouth shark, a deep water filter feeder. In the LRT Megachasma nests between Cladoselache and all higher sharks. It is the basalmost shark with single cusp teeth. The rostrum extends slightly over the mouth with anteriorly-oriented nares.

Agassiz L 1838. Recherches Sur Les Poissons Fossiles. Tome III (livr. 11). Imprimérie de Petitpierre, Neuchatel 73-140.

Taylor LR, Compagno LJV and Struhsake PJ 1983. Megamouth – a new species, genus, and family of lamnoid shark (Megachasma pelagios, family Megachasmidae) from the Hawaiian Islands. Proceedings of the California Academy of Sciences. 43 (8): 87–110.

Smith A 1829. Descriptions of new, or imperfectly known objects of the animal kingdom, found in the south of Africa. South African Commercial Advertiser 3: 2.

wiki/Megachasma
wiki/Megamouth_shark
wiki/Orodus