THE CLADID CRINOID BARYCRINUS FROM THE BURLINGTON LIMESTONE (EARLY OSAGEAN) AND THE PHYLOGENETICS OF MISSISSIPPIAN BOTRYOCRINIDS

Abstract

All species of Barycrinus from the early Osagean Burlington Limestone of the United States midcontinent are reviewed. Burlington Barycrinus species include: B. rhombiferus (Owen and Shumard, 1852); B. magister (Hall, 1858); B. spurius (Hall, 1858); B. crassibrachiatus (Hall, 1860); B. scitulus (Meek and Worthen, 1860) n. combination; and B. sampsoni Miller and Gurley, 1896. Cyathocrinus latus Hall, 1861a, is here considered a junior synonym of B. rhombiferus. The stratigraphic practice of dividing the Burlington into upper and lower parts, for purposes of reporting species ranges, is evaluated.Morphologic data from these Burlington species are combined with data from late Osagean and Meramecian botryocrinid species of Barycrinus and Meniscocrinus, plus four species of Devonian and Mississippian Costalocrinus in a parsimony-based phylogenetic analysis of Mississippian botryocrinids. Results of this analysis indicate that 1) species of Barycrinus form a monophyletic clade that radiated rapidly during the Osagean; 2) B. rhombiferus may have been ancestral to all other Barycrinus species; and 3) M. magnitubus forms a clade with the Mississippian C. cornutus (Owen and Shumard, 1850) and the Devonian C. rex McIntosh, 1984.