Description

Middle Miocene

Round Mountain Silt, Sharktooth Hill Bonebed

Bakersfield, Kern County, CA, USA

Great blue 32mm shark tooth

Shark.

Isurus planus has been traditionally classified as a mako but it may be reassigned to the genus, Carcharodon to reflect a closer relationship to the great white shark.  It is apparently a descendant or sister taxon of Carcharodon hastalis which was the direct ancestor of the great white shark.  I. planus is best-known from the Sharktooth Hill Bonebed but it is also known from other Middle to Late Miocene sites in California, Mexico and perhaps the Early-Middle Miocene of Australia.