caa a22 4500 388017724 CHVBK 20180307124915.0 cr unu---uuuuu 161130e199805 xx s 000 0 eng 10.1017/S0022336000024276 doi S0022336000024276 pii (NATIONALLICENCE)cambridge-10.1017/S0022336000024276 Ausich William I. Department of Geological Sciences, 155 South Oval Mall, The Ohio State University, Columbus, 43210 <ausich@mps.ohio-state.edu> Early phylogeny and subclass division of the Crinoidea (Phylum Echinodermata) [Elektronische Daten] [William I. Ausich] A stepwise approach is employed to determine the phylogeny of the initial crinoid radiation during the Arenig and Llanvirn series of the Ordovician. Parsimony-based character analysis is completed first on Arenig crinoids and then for Arenig and Llanvirn crinoids combined. The topology from well-resolved trees of this early crinoid radiation indicates that the Crinoidea should be subdivided into six subclasses. A new subclass and new order, Aethocrinea and Aethocrinida, respectively, are proposed for crinoids with four circlets of plates in the aboral cup: lintels, infrabasals, basals, and radials. This aboral cup construction is best displayed by Aethocrinus, one of the oldest known crinoids (?Tremadoc-Arenig). However, this primitive aboral cup construction is also present in two Llanvirn crinoids, Perittocrinus and Tetracionocrinus. The Aethocrinea was a small, short-lived radiation of crinoids with this design that was different from those of other crinoids. Two families in the Aethocrinida are the Aethocrinidae, which includes Aethocrinus, and the Perittocrinidae, which includes Perittocrinus and Tetracionocrinus. In addition to the Aethocrinea, the following crinoid subclasses are recognized based on character analyses of these earliest crinoids: Cladida, Camerata, Disparida, Flexibilia, and Articulata. Copyright © The Paleontological Society Journal of Paleontology Cambridge University Press 72/3(1998-05), 499-510 0022-3360 72:3<499 1998 72 JPA https://doi.org/10.1017/S0022336000024276 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1017/S0022336000024276 text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Ausich William I. Department of Geological Sciences, 155 South Oval Mall, The Ohio State University, Columbus, 43210 <ausich@mps.ohio-state.edu> NATIONALLICENCE 773 0- Journal of Paleontology Cambridge University Press 72/3(1998-05), 499-510 0022-3360 72:3<499 1998 72 JPA CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-cambridge