Broad snouted cladoselachian with sensory specialization at the base of modern chondrichthyans

Throughout the Silurian and Devonian, cartilaginous fish successively evolved their specialized skeletal and dental characteristics, and increasingly refined their sensory systems. The Late Devonian shark taxon Maghriboselache mohamezanei gen. et sp. n. from the eastern Anti-Atlas of Morocco is known from multiple specimens preserving most of its skeletal features, which in some instances are preserved in three dimensions. Key details of the dentition, jaws, and pectoral skeleton are shared with the iconic genus Cladoselache. Phylogenetic analyses place the family Cladoselachidae as the sister group of symmoriiforms and these groups as sister group of the holocephalans. Further phylogenetic results corroborate that the initial evolutionary radiation of crown chondrichthyans occurred within or before the Late Devonian. Remarkably, this new stem holocephalan is equipped with a wide snout and large laterally separated nasal capsules: the earliest known example of this condition in the chondrichthyan and (perhaps) gnathostome record. This suggests sensory specialization approaching that of extant broad-rostrum elasmobranchs and represents a significant addition to increasingly apparent ecomorphological diversity among early chondrichthyans.

Automated summary

During the Silurian and Devonian periods, cartilaginous fish developed specialized skeletal and dental features and improved their sensory systems. Fossils of a new species called Maghriboselache mohamezanei were discovered in Morocco, which shares key skeletal features with the iconic genus Cladoselache. Phylogenetic analysis reveals the evolutionary relationship between different shark families, indicating that the initial radiation of crown chondrichthyans occurred in the Late Devonian. The discovery of this new stem holocephalan provides insights into the sensory specialization and ecological diversity of early chondrichthyans.