Journal of Paleontology, 92(5), 2018, p. 850–871 Copyright © 2018, The Paleontological Society 0022-3360/18/0088-0906 doi: 10.1017/jpa.2017.154


Disparid and hybocrinid crinoids (Echinodermata) from the Upper Ordovician (lower Katian) Brechin Lagerstätte of Ontario


William I. Ausich,1 David F. Wright,2 Selina R. Cole,2 and Joseph M. Koniecki3


1School of Earth Sciences, 125 South Oval Mall, The Ohio State University, Columbus, Ohio 43210 ⟨ausich.1@osu.edu⟩ 2Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, P.O. Box 37012, MRC 121, Washington, DC


20013-7012 ⟨wrightda@si.edu⟩⟨colesel@si.edu⟩ 33529 E. Joy Rd, Ann Arbor, Michigan 48105 ⟨paleojk@gmail.com⟩


Abstract.—The Brechin Lagerstätte (Katian, Ordovician) from the Lake Simcoe region of Ontario, Canada contains a diverse array of echinoderms. Here, we describe seven disparid and two hybocrinid crinoids (subclass Pentacrino- idea, infraclass Inadunata), including a new disparid species belonging to the Anomalocrinidae (order Homocrinida). In total, the disparids include Anomalocrinus astrictus n. sp.; Cremacrinus guttenbergensis Kolata, 1975; C. inaequalis Billings, 1859; Daedalocrinus bellevillensis Billings, 1883; Eustenocrinus springeri Ulrich, 1925; Iocrinus trentonensis Walcott, 1883; and Isotomocrinus tenuis Billings, 1857b. The hybocrinids include Hybocrinus tumidus Billings, 1857a and Hybocystites problematicus Wetherby, 1880. Previously known from only the holotype, three additional specimens of E. springeri expand our understanding of this unusual crinoid. Nomenclatural acts include: (1) the recommended designation of D. kirki Ulrich, 1925 as a junior synonym of D. bellevillensis is followed; (2) Hybocrinus pristinus Billings, 1858 is designated as a junior synonym of H. tumidus, and previous decisions are followed to retain Hybocystites eldonensis (Parks, 1908) as a junior synonym of H. problematicus; (3) although probably assignable to Anomalocrinus Meek and Worthen, 1865, the aberrant crinoid Glaucocrinus falconeri Parks and Alcock, 1912, and its genus Glaucocrinus Parks and Alcock, 1912, are designated as nomena dubia; (4) Iocrinus similis (Billings, 1857) is also designated as a nomen dubium; and (5) Iocrinus subcrassus torontoensis Fritz, 1925 is designated a junior synonym of I. subcrassus Meek and Worthen, 1865.


UUID: http://zoobank.org/90f8580b-ed7e-4405-97b2-73c9069de7f5 Introduction


Upper Ordovician (lower Katian) rocks from the upper Bobcaygeon−lower Verulam Formation interval in the Lake Simcoe region of Ontario, Canada are well known for their excep- tionally preserved echinoderm fauna and for well-exposed hard- grounds that supported a diverse shallow-marine fauna. Numerous taxa in this fauna are known completely, from the arms/brachials to the attachment structure,which is most unusual and whywe refer to this fauna as the Brechin Lagerstätte (Cole et al., 2018). Study of upper Bobcaygeon Formation−lower Verulam For-


mation echinoderms began with thework of Billings (1856, 1857a, 1858, 1859). Further, several studies have addressed the paleoe- cology of this remarkable echinoderm occurrence (e.g., Brett and Liddell, 1978; Brett and Brookfield, 1984; Brett and Taylor, 1999; Brett et al., 2008). However, the last general systematic evaluation of the entire crinoid fauna was by Springer (1911). Since then, the systematics of a few taxa have been studied (e.g., Guensburg, 1992), but a comprehensive taxonomic evaluation is much needed. This study is part of a larger reevaluation of crinoids from the Brechin Lagerstätte. This contribution considers only the disparid and hybocrinid crinoids (subclass Pentacrinoidea, infraclass Inadunata) and is preceded by that of Cole et al. (2018),


which evaluated the dicyclic camerate crinoids (subclass Camerata) of theBrechin Lagerstätte. Future studies in this series will include a re-evaluation ofmonocyclic camerate crinoids and all other species belonging to the Pentacrinoidea (e.g., eucladids and flexibles, see Wright et al., 2017). Katian crinoid faunas are of particular importance to our


understanding of crinoid evolutionary history because they represent upper tiering levels of communities at the culmination of the Great Ordovician Biodiversification Event (GOBE; Webby et al., 2004; Ausich and Deline, 2012; Wright and Toom, 2017). These faunas are from the final stages of the early Paleozoic crinoid evolutionary fauna and are among the last faunas that thrived in shallow epicontinental seas prior to the Late Ordovician extinctions that resulted from global climate change and habitat destruction (e.g., Sheehan, 2001; Brenchley et al., 2003; Peters and Ausich, 2008). In this paper, we describe all known disparid and hybo-


crinid crinoids from the Brechin Lagerstätte, including a new species of disparid belonging to the Anomalocrinidae (order Homocrinida). Our descriptions and taxonomic reassessments include the disparids Anomalocrinus astrictus n. sp.; Cremacrinus guttenbergensis Kolata, 1975; Cremacrinus inaequalis Billings, 1859; Daedalocrinus bellevillensis


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