A new early Cretaceous clupeomorph fish from the Arratia Valley, Basque Country, Spain

Abstract

Fish-bearing beds of early Cretaceous age crop out in the Arratia Valley, province of Biscay, along the nucleus of the Bilbao Anticlinorium in the Basque-Cantabrian Basin, northern Spain. Teleost fossils have been found in several stratigraphic levels, dated as Valanginian–Barremian, in the Villaro Member of the Villaro Formation. The Villaro Member is a 1100-m-thick succession of black shales, sandstones and scattered limestones that represent deposition in a shallow lacustrine system periodically fed by delta prograding bars and channels. Deposition took place in a restricted freshwater–brackish environment that was occasionally affected by marine incursions. The first new taxon from the Arratia Valley, described here, isEzkutuberezi carmeni gen. nov., sp. nov., a deep-bodied clupeomorph whose autapomorphies include: a posterior supramaxilla with a long anterior process forming an angle of 90° with the main body of the bone; a hypertrophied, claw-shaped last dorsal scute; only two epurals; and hypural 3 with a submedian longitudinal crest. The morphology of the dorsal scutes supports its assignment to the paraclupeid subfamily Paraclupeinae within the order Ellimmichthyiformes. The new taxon is the oldest European clupeomorph, and the first articulated vertebrate fossil to be described from the Basque-Cantabrian Basin.