Abstract
Tamiobatis vetustus is a very rare Paleozoic shark, originally based on a well-preserved, isolated brain-case of somewhat doubtful provenance from Eastern Powell Co., Kentucky. A second much larger braincase has been referred to the genus but, like the holotype, is completely isolated. The latest specimen, found on a bedding plane in the Late Devonian Cleveland Shale, is associated with partial jaws, teeth, scales, and a spine impression which demonstrates that it is a ctenacanthoid shark, herein assigned to the family Tamiobatidae Hay, 1902. The well-preserved basicranial region reveals details of the blood circulation pattern not previously seen.