Evolutionary origins and development of saw-teeth on the sawfish and sawshark rostrum

Abstract

A well-known characteristic of chondrichthyans (e.g. sharks, rays) is their covering of external skin denticles (placoid scales), but less well understood is the wide morphological diversity that these skin denticles can show. Some of the more unusual of these are the tooth-like structures associated with the elongate cartilaginous rostrum ‘saw’ in three chondrichthyan groups: Pristiophoridae (sawsharks, Selachii), Pristidae (sawfish, Batoidea) and the fossil Sclerorhynchoidea (Batoidea).