Journal of Paleontology, 92(3), 2018, p. 488–505 Copyright © 2018, The Paleontological Society 0022-3360/18/0088-0906 doi: 10.1017/jpa.2017.151


An echinoderm Lagerstätte from the Upper Ordovician (Katian), Ontario: taxonomic re-evaluation and description of new dicyclic camerate crinoids


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


1Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, P.O. Box 37012,MRC121, Washington,DC20013- 7012 ⟨colesel@si.edu⟩; ⟨wrightda@si.edu⟩ 2School of Earth Sciences, The Ohio State University, Columbus, Ohio, 43210 USA ⟨ausich.1@osu.edu⟩ 33529 E. Joy Rd, Ann Arbor, MI 48105 ⟨paleojk@gmail.com⟩


Abstract.—The Upper Ordovician (lower Katian) Bobcaygeon and Verulam formations from the Lake Simcoe region of Ontario contain a highly diverse echinoderm assemblage that is herein recognized as a Konservat-Lagerstätte. Although fossil crinoids have long been recognized from these formations, the fauna has not received a comprehensive taxonomic evaluation since Springer’s classic 1911 monograph. Recent extensive collection and preparation of new material from the Bobcaygeon and Verulam formations near Brechin, Ontario recovered numerous exceptionally preserved crinoid specimens with arms, stems, and attachment structures intact. The Brechin Lagerstätte is the most taxonomically diverse Katian crinoid fauna, with more than 20 crinoid genera represented in this collection. Here, all dicyclic crinoids belonging to subclass Camerata from the Brechin Lagerstätte are evaluated. The


following four genera and seven species are described from the fauna, including one new genus and four new species: Reteocrinus stellaris, Reteocrinus alveolatus, Archaeocrinus sundayae n. sp., Archaeocrinus maraensis n. sp., Priscillacrinus elegans n. gen. n. sp., Cleiocrinus regius, and Cleiocrinus lepidotus n. sp. The exceptional preservation of this collection provides an opportunity to describe more fully the morphologic and ontogenetic details of known Ordovician crinoid taxa, to conduct a taxonomic re-evaluation of many species, to describe new taxa, and to provide a framework for subsequent studies of crinoid community paleoecology.


UUID: http://zoobank.org/e3e268a7-88e5-43cd-84ea-b40df45e8281 Introduction


The Middle to Late Ordovician was an important interval in the early evolutionary history of crinoids. Following their earliest known occurrence in the Lower Ordovician (Tremadocian), crinoids underwent a major taxonomic radiation as part of the Great Ordovician Biodiversification Event (GOBE) (Ausich and Deline, 2012; Wright and Toom, 2017), which has been recog- nized globally across diverse invertebrate groups (Webby et al., 2004). For most crinoid clades, peak diversity was reached during the Sandbian to Katian (Peters and Ausich, 2008; Cole et al., 2017). As a result, crinoid assemblages from this interval represent the earliest development of complex crinoid commu- nities with high species richness, high morphological disparity, and diverse niche space occupation (Foote, 1994, 1999; Brower, 2007; Deline, 2009; Deline et al., 2012). Thus, increased documentation of the morphology and taxonomic diversity of crinoids from this interval is important for studies of crinoid paleoecology, phylogeny, and macroevolutionary trends. Fossil crinoids are well known from the Upper Ordovician


(Sandbian–Katian) rocks of southern Ontario, particularly from the Bobcaygeon and Verulam formations in the Lake Simcoe region. Although this crinoid fauna has been recognized for nearly a century and a half (e.g., Billings, 1858, 1859;


Springer, 1911), little attention has been paid to the taxonomy of the crinoids within the fauna. Recent extensive collection of echinoderm material from the Bobcaygeon and Verulam forma- tions near Brechin, Ontario has produced extensive collections of complete crinoid specimens, many with arms, stems, and attachment structures intact. The exceptional preservation of the recovered echinoderm material merits the designation of the fauna as a Konservat-Lagerstätte, and it is subsequently referred to herein as the “Brechin Lagerstätte.” This study provides a comprehensive re-evaluation of the dicyclic camerate crinoids from the Brechin Lagerstätte by reviewing taxonomic assign- ments, revising species descriptions to include morphological features that were previously unknown, and describing new taxa. In this contribution, we discuss all known taxa from the Brechin Lagerstätte that belong to Diplobathrida sensu Cole (2017) as well as the dicyclic stem eucamerates (i.e., reteocrinids). In a series of subsequent papers, we will address the monobathrid, cladid, disparid, flexible, and hybocrinid crinoids from the fauna.


Stratigraphy and geologic setting


The Brechin Lagerstätte crinoids described herein were recov- ered from multiple horizons of the Bobcaygeon and Verulam formations exposed in the vicinity of Brechin, Ontario (Fig. 1).


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