Protodus jexi Woodward, 1982 (Chondrichthyes), from the Lower Devonian Campbellton Formation, New Brunswick, Canada

Protodus jexi from the early Emsian 'Atholville beds', Campbellton Formation between Atholville and Campbellton, northern New Brunswick, Canada, is redescribed from material studied by R.H. Traquair and new specimens. Protodus is a valid monotypic genus with rows of shark-like serrated teeth. The taxon is based solely on teeth, some of which are associated. The teeth have monocuspid crowns with a thin enameloid layer and distinctive labial depressions or grooves, and large subrectangular to D-shaped cladodont-like bases some laterally and downwards extended. Crown histology is orthodentine merging down into the osteodentine of the base. A possible relationship with cladodont-bearing sharks is mooted and Protodus and other putative late Silurian to early Devonian chondrichthyan teeth are referred to a redefined family Protodontidae WOODWARD.