Stratigraphical and geographical distribution of Mississippian (Lower Carboniferous) Crinoidea from England and Wales

Abstract

SUMMARY Sixty genera of Mississippian crinoids, comprising 191 species, are evaluated from 83 localities in England and Wales, based on modern revisions from the literature, study of museum collections and new field work. These genera occurred through ten time units in the Mississippian (Tournaisian–Serpukhovian). Among the 191 species, 161 are considered valid with 28 requiring new combinations of genus and species names. Twelve species are considered nomina dubia, one species is considered a nomen nudum, three species cannot be assigned with certainty to a genus, and 14 can only be assigned at the generic level. Hastarian (Times 1 and 2) faunas have a very low generic richness with only one genus known. Ivorian (Time 3) faunas have a substantially higher generic richness with 21 genera known. Chadian faunas have the highest generic richness with 28 genera from the lower Chadian (Time 4) and 19 genera from the upper Chadian (Time 5). Post-Chadian faunas include those from the Arundian (Time 6), Holkerian (Time 7), Asbian (Time 8), Brigantian (Time 9) and Pendleian (Time 10); all have low generic richness with 0, 4, 7, 13 and 7 genera known, respectively. The dominant Mississippian crinoid faunas are on Ivorian carbonate ramps, Chadian Waulsortian and Waulsortian-related facies, and in the Pendleian marine beds that supported Woodocrinus. In comparable facies, the composition of faunas is similar in England and Wales and North America, although generic richness is commonly lower in England and Wales. The overall crinoid fauna has much lower generic richness in England and Wales than in North America because the stratigraphical record of England and Wales preserves a much lower diversity of crinoid-bearing facies. The critical Arundian-Holkerian interval for Palaeozoic crinoid history is poorly represented in England and Wales.