Swiss Journal of Palaeontology (2018) 137:265–277 https://doi.org/10.1007/s13358-018-0161-1 (0123456789().,-volV)(0123456789().,-volV) REGULAR RESEARCH ARTICLE Mississippian–Permian evolution and paleogeographic distribution of the Cromyocrinidae and Pirasocrinidae (Crinoidea, Dendrocrinida) Gary D. Webster1 Received: 9 May 2018 / Accepted: 25 August 2018 / Published online: 3 October 2018 Ó Akademie der Naturwissenschaften Schweiz (SCNAT) 2018 Abstract Late Paleozoic macroevolutionary crinoid faunas were dominated by dendrocrinids, replacing most of the camerata crinoids that had dominated the Early and Middle Paleozoic macroevolutionary crinoid faunas. Two dendrocrinid taxa, the Cromyocrinidae and Pirasocrinidae, first recognized in the Mississippian (Vise´an), attained their greatest generic diversity in the late Moscovian to early Kasimovian, declined in the Late Pennsylvanian and Early Permian, and became extinct in the Late Permian or end-Permian extinction event. The paleontologic record of the Cromyocrinindae and Pirasocrinidae is best documented from the Midcontinent of the United States and both are recognized worldwide in the Late Paleozoic. Their diversity in the latest Pennsylvanian and Early Permian is probably greater than currently recognized because disarticulated ossicles that are ascribed to one or the other of the two families in described faunas are commonly not recognizable at the genus level. Both families show individual evolutionary trends while following the general evolutionary trends of the dendrocrinids. Keywords Cromyocrinidae Á Pirasocrinidae Á Evolution Á Pennsylvanian radiation/decline Á Diversity Á Paleogeography Introduction based on the genera and species of both families it should be noted that I do not agree with all of the species identi- Paleozoic crinoids were broken into three macroevolu- fications and some species should perhaps be placed in tionary faunas by Ausich and Kammer (2006) wherein they synonymy with other species of the same or a different recognized that the Middle Paleozoic macroevolutionary genus. However, a systematic review of the genera or faunas were dominated by camerate crinoids and replaced species is beyond the scope of this paper and no species are by the dendrocrinids in the Late Paleozoic macroevolu- specified although their stratigraphic occurrence and geo- tionary faunas. Webster (2012) reviewed some of the graphic occurrences are used for stratigraphic range and classification changes recognized within the Middle and paleogeographic distribution interpretations. For complete Late Paleozoic cladid crinoids when he reviewed Devonian references and synonymies of each of the genera listed see evolution of three superfamilies of the cyathocrininids and Webster and Webster (2014) which also includes syn- the primitive, transitional and advanced forms of the onymies for all species of each genus. Devonian dendrocrinids. Geochronologic terms used herein are given in Fig. 1. This summary of the evolution and paleogeographic Although many boundaries of the international distribution of cromyocrinids and pirasocrinids does not geochronologic terms for the Carboniferous have been include species based on disarticulated plates, or specimens finalized, a few have working proposals for diagnostic identified as cf., aff., (?), or spp. Although this review is fossils and stratotypes that still require ratification (Richards 2013). For example, the Serpukhovian basal boundary used herein is equated to the base of the Editorial Handling: Ben Thuy. Namurian until a decision is made on one of the two pro- posed boundary stratotypes and the diagnostic fossil taxon. & Gary D. Webster [email protected] The status of the Permian international geochronologic terms was summarized by Lucas and Shen (2017). 1 School of the Environment, Washington State University, Geochronologic terms used herein follow the ratified Pullman, WA 99164-2812, USA 266 G. D. Webster Fig. 1 Correlation of International System or International Stages North American Stages international geochronologic Subsystem and North American stages Changhsingian Ochoan Wuchiapingian Capitanian Capitanian Permian System Wordian Wordian Roadian Roadian Kungurian Leonardian Artinskian Sakmarian Asselian Wolfcampian Gzhelian Virgilian Kasimovian Missourian Pennsylvanian Subsystem Desmoinesian Moscovian Atokan Bashkirian Morrowan Serpukhovian Chesterian Viséan Meramecian Mississippian Subsystem Osagean Tournaisian Kinderhookian boundary terms and proposed working boundaries as given genera, with or without coarse nodose or ridge ornament, by Richards (2013) and Lucas and Shen (2017). North one to three anal plates, pores along the cup sutures giving American terms are used for the Pennsylvanian until the them a stitched appearance, impressed sutures, intracup proposed international geochronologic term boundaries are facets bearing fine ridges radiating away from the suture ratified and because most of the species are from North pores, lack of a plated tegmen, and an arm girdle in the America. proximal part of the arms when enclosed (Table 1). The stem is normally round in cross-section and may be very robust and lengthy suggesting they were middle and upper Cromyocrinidae tier feeding organisms. Disarticulated cup ossicles are easily recognized by the The Cromyocrinidae (Bather 1890) is herein considered a combination of the general thickness, of cup plates, orna- Late Paleozoic clade that originated in the Mississippian ment (if present), and the intracup facet morphology (if (Visean) and ended in the Late Permian or with the end- preserved or observable). However, generic identification Permian extinction event. They are characterized by their of the disarticulated ossicles is commonly not possible moderate to large adult size, elongate cylindrical crown, unless articulated cups or crowns are known from the same globose or bowl-shaped cup, with or without a shallow to stratigraphic horizon at the same or in a nearby locality. deep basal concavity, relatively thick cup plates in most Evolution and paleogeographic distribution of the Cromyocrinidae and Pirasocrinidae 267 Table 1 Stratigraphic occurrences of cromyocrinid genera Genera Miss. Pennsylvanian Permian Visean Serpukhovian Morrowan Atokan Desmoinesian Missourian Virgilian Asselian Sakmarian Artinskian Kungurian Roadian Moapacrinus X? X ?? Probletocrinus X Hemiindocrinus XX X Minilyacrinus XXX X Parulocrinus XX? X Ulocrinus XXX Parethlocrinus XX Aaglaocrinus XX X X Metacromyocrinus XXX Paracromyocrinus XX X Tarachiocrinus XXX Aglaocrinus XXXX Diphuicrinus XXX X Synarmocrinus XXX Mathericrinus XXX X X Ethelocrinus XXXX Mooreocrinus XXXXX Dicromyocrinus XXXXX Goleocrinus XXX Cromyocrinus XXX Manikosocrinus XX Tyrieocrinus XX Ureocrinus XX 268 G. D. Webster Moore and Strimple (1978a) in Moore and Teichert Timor as well as the Sakmarian into the Kungurian or (1978, p. T694, T701), recognized 12 genera in the Roadian of Australia. Although most of the occurrences of Cromyocrinidae and 4 genera in the Ulocrinidae Moore the cromyocrinids are in warm equatorial environments, in and Strimple 1973. Webster (1981) revised the Cromy- Western Australia they were living in the cooler waters of ocrinidae and Ulocrinidae, recognizing 20 named genera higher latitudes approaching 60°S latitude (Webster and and four unnamed specimens assigned to the cromyocrinids Jell 1992). by various authors. He ran a combined cluster analysis and Dendrocrinids underwent three general evolutionary principal component analysis of the genera of both fami- trends in the Paleozoic that included; 1, Modification of the lies. He concluded that the two families could be separated cup shape from a vase to a bowl or disc; 2, Loss of anals into three groups with a central subgroup of two genera. All from more than three to one or none; and 3, Brachial groups were based on the cup shape, arm number and development from uniserial to biserial as noted by branching pattern. Because each of those morphologic numerous workers over the last century. The cromy- characters were considered to evolve polyphyletically ocrinids, throughout their increase in diversity followed by within the family it was not possible to use them for their decline and extinction, paralleled the dendrocrinid diagnostic characters for each group or define them as general evolutionary patterns with some additional evolu- separate families. Lacking other characters that could be tionary modifications, including the following. exclusively used to define a family he judged the Ulocri- 1. Cup shape. The Middle and Late Vise´an plesiomorphic nidae to be a junior synonym of the Cromyocrinidae. cup of Ureocrinus has a medium vase shape with Currently, there are 23 genera and 147 species assigned weakly upflared infrabasals and gently incurling radi- to the Cromyocrinidae as compiled by Webster and Web- als (Table 2). In the late Vise´an, the apomorphic ster (2014). Surprisingly, 21 genera are based on crowns globose cup of Tyrieocrinus and medium bowl cups of with only two genera (Tyrieocrinus and Hemiindocrinus) Mantikosocrinus and Cromyocrinus are recognized and based on cups (Table 1). continue into the Permian in Hemiindocrinus (globose) Stratigraphic ranges of most cromyocrinid species are and Moapacrinus (medium bowl). Many of the apo- restricted to one series as compiled by Webster and Web- morphic medium bowl cups have gently to moderately ster (2014). However, the stratigraphic ranges of most distal incurling radials giving them a globular appear- genera