First occurrence of Tiaracrinus (Crinoidea, Zophocrinidae) in the Devonian of Iberia: Biostratigraphical, palaeoecological, and palaeogeographical implications

Abstract

Representatives of the crinoid genus Tiaracrinus are known from the Lochkovian to Eifelian (Early–Middle Devonian) of several countries, in Europe and North Africa. In this work, we describe the first occurrence of this taxon in the Devonian period of Iberian Massif (Iberia). Here, we report three specimens (two from the São Pedro da Cova region within Valongo anticline in northwestern Portugal and one from the Cantabrian Mountains in northern Spain), which are described to the type species Tiaracrinus quadrifrons. These new fossil findings provide new knowledge about the stratigraphic and geographic distribution of the genus Tiaracrinus and species T. quadrifrons. The co‐occurrence of T. quadrifrons in the Devonian outcrops of Valongo anticline also more precisely constrains the Devonian formations in age (Emsian–Eifelian) in that Portuguese region. In the palaeoecological and palaeoenvironmental context, this species coexisted with other crinoid species and representatives of several other groups of marine benthic invertebrates in a shallow water coral reef environment, with oxygenated substrates and regular salinity levels (mixoeuhaline environment). In addition, the presence of fine sediments with ripples suggests a low velocity current enough to reorient concentrations of tentaculite shells.