Late Devonian (Famennian) chondrichthyes from Mexico

The Paleozoic vertebrate fossil record from Mexico is very scarce and strongly biased by rock exposure, composed mainly of upper Paleozoic (Carboniferous and Permian) outcrops (e.g., Sánchez-Zavala et al., 1999; Poole et al., 2005; González- Rodríguez et al., 2013). In particular, the Mexican Paleozoic fish fossil record comprises a few isolated chondrichthyan scales and some semiarticulated symphysial tooth whorls belonging to the iconic shark Helicoprion, with ages ranging from the Late Carboniferous to the early Permian. The first reported Paleozoic fish from Mexico belongs to a semiarticulated symphysial tooth whorl of Helicoprion mexicanus from the Permian of Coahuila, near Las Delicia…