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This article describes the crinoid Euspirocrinus varbolaensis sp. nov. from the early Silurian (Rhuddanian) of northern Estonia. Discovered within the lower Rhuddanian strata in the Reinu quarry, Rapla Parish, this is the second Rhuddanian species of Euspirocrinus from Estonia. Its discovery further documents the rapid faunal recovery of early Silurian crinoids following the Late Ordovician biotic crisis. This find supports the hypothesis that the early Silurian recovery of crinoids was primarily the result of the diversification and migration of Laurentian clades. [ABSTRACT FROM AUTHOR]

A diverse echinoderm fauna lived in reef and non-reef Silurian facies of the upper Midwestern USA. However, these faunas are dominantly preserved in dolostones with moldic preservation, and fossils from dolostone facies have not been documented to the extent of Silurian crinoids in nondolostone strata. Herein, an echinoderm fauna is described from the dolostones of the Cedarville Member of the Laurel Limestone (Wenlock, Homerian) from the Pepcon Cement Quarry in west-central Ohio. The described fauna contains blastoids, hemicosmitoids, and crinoids, including Troosticrinus subcylindricus (Hall and Whitfield, 1875); Caryocrinites sp. indet.; an unidentifiable diplobathrid camerate; Periechocrinus tennesseensis (Hall and Whitfield, 1875); Periechocrinus egani ? (Miller, 1881); Stiptocrinus farringtoni (Slocom, 1908); Calliocrinus primibrachialis Busch, 1943; Calliocrinus poepplemani new species; Calliocrinus hadros new species; and Lecanocrinus sp. indet. Generic concepts for the Eucalyptocrinitidae are clarified; and, surprisingly, Eucalyptocrinites Goldfuss, 1831 is absent from this fauna. Additionally, lectotypes and paralectotypes are designated for Periechocrinus tennesseensis and Calliocrinus primibrachialis. UUID: http://zoobank.org/a8c8e7e3-9bc3-4078-83bd-5572816366e5 [ABSTRACT FROM AUTHOR]

Nine crinoids are described from the Wooster Shale Member of the Cuyahoga Formation from Wayne and Ashland counties, Ohio, USA. Identifiable elements of the fauna include five camerate crinoids, one flexible crinoid, and three other eucladid crinoids. Five new species are described, including Cactocrinus woosterensis n. sp., Cusacrinus brushi n. sp., Agaricocrinus murphyi n. sp., Decadocrinus laevis n. sp., and Decadocrinus inordinatus n. sp. Overall, the distribution of crinoid clades in the Wooster Shale is similar to that of the stratigraphically lower Meadville Shale Member of the Cuyahoga Formation, although less diverse and with only one species (Cyathocrinites simplex) in common. Many of the Wooster Shale Member crinoids are completely or partially preserved with siderite either in nodules or within siderite beds. These crinoids are commonly preserved in trauma postures, which is characteristic of burial in episodic high turbulence events. The paleoenvironments and taxa of the two Cuyahoga Formation crinoid faunas more closely resemble Viséan faunas in siliciclastic settings than typical carbonate faunas of the Tournaisian. UUID: http://zoobank.org/2d2678e1-2367-4429-bea0-a64cd020e98c [ABSTRACT FROM AUTHOR]

Zygocycloides? foerstei n. sp. is described from the Llandovery (Aeronian) Brassfield Formation of southwestern Ohio. This is among the oldest reported Silurian cyclocystoids from North America and is the only North American Llandovery cyclocystoid that is preserved with a complete rim of marginal ossicles. Zygocycloides Smith and Paul, 1982 is most similar to Nicholsodiscus Glass et al., 2003 (Katian) and Perforocycloides Ewin et al., 2019 (Llandovery, Telychian), both from Anticosti Island, Québec. Cyclocystoids (Ordovician to Mississippian) survived Late Ordovician extinctions, and this discovery documents that this echinoderm clade was part of shallow-water, marine paleocommunities during the initial post-extinction transgression onto the Laurentian platform. UUID: http://zoobank.org/3d3e092e-267b-4841-9245-6275d1eb79a1 [ABSTRACT FROM AUTHOR]

The Ordovician and Silurian are an exceptionally important interval of time for understanding the effects of ancient climate change on the paleobiodiversity of echinoderms. Despite this importance, the fossil record of many echinoderm groups during this interval is sparse. The echinoids, or sea urchins, are no exception; and new fossil finds are necessary to better understand their initial diversification during the lower Paleozoic. We herein report on material from a new genus and species of echinoid, Anticostiechinus petryki gen. et sp. nov., from the Silurian of Anticosti Island, Canada. The morphology of the tubercles and spines of A. petryki are atypical for echinoids, and the surfaces for spine articulation consist of rounded, concave indentations. Additionally, the bases of the spines are subspherical. Furthermore, A. petryki belongs to the family Echinocystitidae, which increases the known diversity and distribution of this family during the Silurian and provides insight into the biogeography of echinocystitids from the Silurian to Devonian. [ABSTRACT FROM AUTHOR]

Gennaeocrinus tariatensis new species is an Emsian (Devonian) monobathrid crinoid described from the Tarvagatay Terrane of Mongolia and part of the Central Asian Orogenic Belt. The Tarvagatay Terrane is an arc terrane that accreted to the southern margin of the Siberian Craton. Gennaeocrinus tariatensis was collected from the Emsian Tariat Formation, a terrigenous sequence of conglomerates, sandstones, and siltstones. Associated faunas include brachiopods, molluscs, and rare tabulate corals. Although Gennaeocrinus is well known from the Emsian–Givetian of North America, this is the first occurrence of the genus outside Laurussia. Mongolia is a large country with many terranes having varied paleogeographic, sedimentological, and tectonic histories; but reports of Paleozoic echinoderms are rare. The crinoid occurrence from the Tariat Formation is from the same age as previously described Emsian crinoids from the Chuluum Formation but differs significantly in sedimentology, paleogeography, and paleolatitude. UUID: http://zoobank.org/d87cb083-4360-41e5-ac90-1b8ef625a31d [ABSTRACT FROM AUTHOR]

Two cupressocrinitids (Crinoidea, Eucladida) from the famous crinoid collection of Dr. Ludwig J.T. Schultze deposited in the Museum of Comparative Zoology (MCZ) are revised in the present study: Cupressocrinites hybridus n. comb. and Halocrinites minor n. comb. The rare C. hybridus has a stratigraphically and regionally restricted occurrence at the Eifelian–Givetian boundary of the Hillesheim Syncline (Eifel, Rhenish Massif, Germany), but the more common H. minor occurs supraregionally from the Eifelian to the Frasnian (Middle to Upper Devonian). Both cupressocrinitids are redescribed on the basis of the type material stored in the MCZ. In addition, the rare Halocrinites heinorum n. sp. from the Eifelian–Givetian boundary beds and lower Givetian of the Eifel (Rhenish Massif, Germany) is described, and Encrinus townsendi (König, 1825) is questionably reassigned to Robustocrinites: R.(?) townsendi n. comb. Pre- and postmortem ossicular modifications of the studied cupressocrinitid skeletons are also discussed. UUID: http://zoobank.org/4598e1fa-8ca5-4160-8fee-6e8c6d444115 [ABSTRACT FROM AUTHOR]

The youngest species of Amphoracrinus, A. tenax new species, is described from the Muldraugh Member of the Borden Formation (early Viséan) of north-central Kentucky. With this new occurrence, both the oldest and youngest named species of Amphoracrinus are from North America. Numerous Tournaisian and Viséan crinoid faunas are documented in the United States, but only four are known to contain Amphoracrinus. Morphological analysis indicates that A. tenax is more closely aligned with species from China than with species from Western Europe or other species from North America, where Amphoracrinus was most diverse and abundant, which has implications for understanding paleogeographic dispersal. The holotype of A. tenax was partially disarticulated on the seafloor before burial, and final burial occurred early during disarticulation. The relative state of disarticulation from pinnules to columnals suggests that plates bound only with ligaments disarticulated as a function of surface area of ligaments binding an articulation. [ABSTRACT FROM AUTHOR]

Despite their importance for understanding phylogeny, character evolution and classification, well‐constrained homology relationships for posterior plating in crinoids have only recently been attempted. Here, we re‐evaluate posterior plate homologies in all major crinoid lineages using development, fossil ontogenies and phylogenetic evidence. Based on these lines of evidence, we change terminology for some posterior plates to correct misnomers and make recommendations for updated terminology of others to better reflect homology. Among pentacrinoids (disparids, hybocrinids, eucladids, flexibles and articulates) the relative position of posterior interray plates, not their topology, reflects homology. From proximal to distal, pentacrinoid posterior plates are the radianal, anal X and right sac plate, regardless of the total number of plates in the adult calyx. Camerate posterior plating contrasts with pentacrinoids, but insufficient data are available to resolve homology relationships between these two clades. More examples of early post‐larval ontogeny are needed in camerates and other Palaeozoic crinoids. [ABSTRACT FROM AUTHOR]

Three new Llandovery (early Silurian) crinoids from Estonia provide an improved understanding of the paleogeographic aspects of the crinoid diversification following the end-Ordovician extinctions. The new taxa are Euspirocrinus hintsae new species (Rhuddanian eucladid), Oepikicrinus perensae new genus new species (Aeronian camerate), and Rozhnovicrinus isakarae new genus new species (Aeronian eucladid). This brings the total of described Llandovery crinoids in Estonia to eight nominal species and a further three taxa in open nomenclature. The Rhuddanian radiation in Baltica mirrored that on Laurentia and Avalonia and was dominated by Ordovician clades that continued to diversify during the Silurian. Known Aeronian crinoids from Estonia continue these clades, whereas new clades diversified on Laurentia and Avalonia. However, by the Wenlock, a largely cosmopolitan fauna existed on Laurentia, Avalonia, and Baltica. UUID: http://zoobank.org/b5e613f1-c211-4676-8967-5a38a7d8d40e [ABSTRACT FROM AUTHOR]

The Kalana Lagerstätte of early Aeronian (Llandovery, Silurian) age in central Estonia preserves a diverse shallow marine biota dominated by non-calcified algae. This soft-tissue flora and decalcified and calcified crinoids are preserved in situ, in a lens of microlaminated, dolomitized micrite interbedded in a sequence of dolomitized packstones and wackestones. Although the Lagerstätte is dominated by non-calcified algae, crinoids (together with brachiopods and gastropods) are among the most common organisms that were originally comprised of a carbonate skeleton. Two new crinoids are described from this unit, Kalanacrinus mastikae n. gen. n. sp. (large camerate) and Tartucrinus kalanaensis n. gen. n. sp. (small disparid). Interestingly, these two crinoids display contrasting preservation, with the more common large camerate preserved primarily as a decalcified organic residue, whereas the smaller disparid is preserved primarily in calcite. Preservation was assessed using elemental mapping of C, Ca, S, and Si. Columns have the highest portion of Ca, once living soft tissue is indicated by C, S was dispersed as pyrite or associated with organics, and Si is probably associated with clay minerals in the matrix. This new fauna increases our understanding of the crinoid radiation on Baltica following Late Ordovician extinctions. UUID: http://zoobank.org/fb1f98c4-d35a-43f4-aa0d-75e4f8154a13 [ABSTRACT FROM AUTHOR]

A new Lower Devonian fauna from the Iberian Chains (NE Spain) is described. Specimens have been collected from the shaley intervals of the Mariposas Formation dated as early Emsian. These include the camerates Acanthocrinus carsli n. sp., Platyhexacrinus santacruzensis n. sp., Culicocrinus breimeri n. sp., Camerata indeterminate, and an indeterminate eucladid. Compared with other faunas from Spain, this represents a low diversity crinoid assemblage that was probably concentrated in shallow, turbid environments. A summary of crinoids previously described from the Spanish Devonian is reported, which indicates that crinoid faunas become progressively more cosmopolitan during the Devonian. UUID: http://zoobank.org:pub/2debf9fa-11bf-46df-baf1-ab7926031051 [ABSTRACT FROM AUTHOR]

End-Ordovician extinctions had a profound effect on shallow-water benthic communities, including the Crinoidea. Further, recovery after the extinctions resulted in a macroevolutionary turnover in crinoid faunas. Anticosti Island is the most complete Ordovician-Silurian boundary section recording shallow-water habitats. Both new taxa and changes in Anticosti Island stratigraphic nomenclature are addressed herein. New taxa include Becsciecrinus groulxi n. sp., Bucucrinus isotaloi n. sp., Jovacrinus clarki n. sp., Plicodendrocrinus petryki n. sp., Plicodendrocrinus martini n. sp., Thalamocrinus daoustae n. sp., and Lateranicrinus saintlaurenti n. gen. n. sp. The status of Xenocrinus rubus as a boundary-crossing taxon is confirmed, range extensions of several taxa are documented, and the distribution of crinoids with the revised stratigraphic nomenclature is documented. UUID: http://zoobank.org/19613a44-ec69-47d7-88ab-fcf88ba771f0. [ABSTRACT FROM AUTHOR]

Using polarized light microscopy, the large, triangular or cylindrical second brachial plate of the Petalocrinidae is demonstrated to be a compound brachial formed through fusion of brachial plates along the distal margin of the growing arms. Based on the number of ambulacral bifurcations, brachials from the primibrachitaxis through at least the quintibrachitaxis may have been fused to form this large plate. In Petalocrinus, fused brachials form a second brachial that assumed the same crystallographic orientation, but in Spirocrinus, multidirectional extinctions preserve some of the original multiplate arrangement. [ABSTRACT FROM AUTHOR]

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 Pentacrinoidea, 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 [ABSTRACT FROM AUTHOR]

The Batocrinidae are characteristic faunal elements in Lower Mississippian shallow-marine settings in North America. Recent delineation of objectively defined genera allows a reexamination of batocrinid species and their distribution in the Fort Payne Formation (early Viséan, late Osagean), a well-studied array of carbonate and siliciclastic facies. The Fort Payne batocrinid fauna has 14 species assigned to six genera, plus hybrid specimens. Magnuscrinus spinosus (Miller and Gurley, 1895a) is reassigned to its original placement in Eretmocrinus. Hybrid specimens (Ausich and Meyer, 1994) are regarded as Eretmocrinus magnificus × Eretmocrinus spinosus. Macrocrinus casualis is the dominant species of Macrocrinus in the Fort Payne, and M. mundulus and M. strotobasilaris are recognized in the Fort Payne Formation for the first time. Magnuscrinus cumberlandensis n. sp. is named, 13 species are designated as junior synonyms, the name for the hybrid specimens is changed to Eretmocrinus magnificus × Eretmocrinus spinosus, and the previous occurrences of two species in the Fort Payne are rejected. The Eastern Interior Seaway was a mixed carbonate-siliciclastic setting with both shallow- and deep-water epicontinental sea facies ranging from relatively shallow autochthonous green shales to deep-water turbidite facies. Dizygocrinus was restricted to shallow-water carbonate and siliciclastic facies, Eutrochocrinus was restricted to shallow-water carbonate facies, and Magnuscrinus was restricted to deep-water facies. Species distributions varied from Abatocrinus steropes, Alloprosallocrinus conicus, Macrocrinus mundulus, and Uperocrinus nashvillae, which occurred throughout the Eastern Interior Seaway, to species that were restricted to a single facies. Eretmocrinus magnificus, Alloprosallocrinus conicus, and Uperocrinus robustus were the dominant batocrinids in the Fort Payne Formation. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This study reports new crinoid material, which is identified as Muicrinus dawanensis new genus and new species from South China, representing the oldest known iocrinid in the world. These new fossils, which are characterized by bearing simple primibrachials and a helically coiled column, are from the lower-middle part of the Dawan Formation, which ranges from the upper Floian (Lower Ordovician) to the lower Dapingian (Middle Ordovician) (∼470 Ma). A total of 11 related taxa with 80 characters were selected to conduct phylogenetic analyses. Our results indicated that South China specimens are closely related to ones that are endemic to Laurentia. Synapomorphies shared between species in those two cratons include elongate supraradial plates and isotomous arm branching. Furthermore, the phylogenetic closeness of endemic taxa that only occurred in two cratons leads us to suggest a geographic connection between those regions during deep time. Combining biogeographic evidence reported from Cambrian studies, this study supports the “missing-link” configuration of Rodinia during the breakup phase. Based on the crinoid global biodiversity pattern updated here, the potential for discovery of new Paleozoic crinoid faunas in China is very high. [ABSTRACT FROM AUTHOR]

Hirnantian (latest Ordovician) localities containing echinoderm fossils are rare; the few that have been discovered primarily contain disarticulated crinoid ossicles. Therefore, relatively little is known about echinoderm evolutionary dynamics across the Late Ordovician - early Silurian boundary, especially noncrinoid echinoderms. New diploporitan echinoderms, Holocystites salmoensis and an unidentified holocystitid, from reefal facies of the Upper Ordovician Ellis Bay Formation of Anticosti Island provide a critical data point concerning diploporitan biogeography and evolutionary pathways undertaken during the Ordovician and Silurian. These fossils also provide a crucial link in understanding the ancestry of the Silurian Holocystites Fauna, an unusual diploporitan fauna from the middle Silurian of North America, whose origination dates back at least 15 million years earlier than previously thought with the discovery of taxa described here. New fossil data such as these stress the importance of uncovering new localities from underrepresented times and places in Earth's history, so that these evolutionary transitions can be better understood. [ABSTRACT FROM AUTHOR]

A major goal of biological classification is to provide a system that conveys phylogenetic relationships while facilitating lucid communication among researchers. Phylogenetic taxonomy is a useful framework for defining clades and delineating their taxonomic content according to well-supported phylogenetic hypotheses. The Crinoidea (Echinodermata) is one of the five major clades of living echinoderms and has a rich fossil record spanning nearly a half billion years. Using principles of phylogenetic taxonomy and recent phylogenetic analyses, we provide the first phylogeny-based definition for the Clade Crinoidea and its constituent subclades. A series of stem- and node-based definitions are provided for all major taxa traditionally recognized within the Crinoidea, including the Camerata, Disparida, Hybocrinida, Cladida, Flexibilia, and Articulata. Following recommendations proposed in recent revisions, we recognize several new clades, including the Eucamerata Cole 2017, Porocrinoidea Wright 2017, and Eucladida Wright 2017. In addition, recent phylogenetic analyses support the resurrection of two names previously abandoned in the crinoid taxonomic literature: the Pentacrinoidea Jaekel, 1918 and Inadunata Wachsmuth and Springer, 1885. Last, a phylogenetic perspective is used to inform a comprehensive revision of the traditional rank-based classification. Although an attempt was made to minimize changes to the rank-based system, numerous changes were necessary in some cases to achieve monophyly. These phylogeny-based classifications provide a useful template for paleontologists, biologists, and non-experts alike to better explore evolutionary patterns and processes with fossil and living crinoids. [ABSTRACT FROM AUTHOR]

A diverse crinoid fauna is described from the Upper Ordovician (Katian) Fombuena Formation from the eastern Iberian Chains of Spain. New crinoids include the diplobathrid camerates Fombuenacrinus nodulus n. gen. n. sp., Goyacrinus gutierrezi n. gen. n. sp., Dalicrinus hammanni n. gen. n. sp., and Ambonacrinus decorus n. gen. n. sp.; the monobathrid camerate Eopatelliocrinus hispaniensis n. sp.; and the cladid Picassocrinus villasi n. gen. n. sp. A new occurrence of Heviacrinus melendezi Gil Cid, Domínguez Alonso, and Silván Pobes, 1996 is also documented from the Castillejo Formation (Darriwilian, Middle Ordovician) from the eastern Iberian Chains of Spain. The Fombuena Formation comprises a Gondwanan crinoid assemblage from a high paleolatitude and has the highest crinoid diversity of any currently known Katian Gondwanan fauna. This assemblage is compared to other Katian age faunas around the globe, and its paleobiogeographic implications are discussed. [ABSTRACT FROM AUTHOR]

Systematic paleontology of three new species of Petalocrinidae (Crinoidea) are documented from the carbonate-dominated units of the Shihniulan and equivalent Leijiatun formations (Llandovery, Silurian) of the Baisha, Fengxiang, and Shuibatang sections in Guizhou (China). New taxa are from the Upper Yangtze Epicontinental Sea of the South China Block. The new taxa include Petalocrinus stenopetalus new species, Spirocrinus circularis new species, and S. dextrosus new species. They have a narrow spatial and temporal (Aeronian) distribution. Evolutionary patterns of the four genera of Petalocrinidae are outlined based on the specialized characters of the fused arm plates. Phylogenetic analysis was used to assess morphological relationships within the Petalocrinidae. Petalocrinus inferior represents the plesiomorphic condition for the group and nests as a sister group of P. stenopetalus n. sp. and the Spirocrinus species used in this analysis and the clade exclusively comprised of Sinopetalocrinus. The phylogenetic analysis suggests that Petalocrinus, as currently defined, might be a paraphyletic genus. [ABSTRACT FROM AUTHOR]

Rhuddanian crinoid faunas are poorly known globally, making this new fauna from the Hilliste Formation of western Estonian especially significant. The Hilliste fauna is the oldest Silurian fauna known from the Baltica paleocontinent, thus this is the first example of the crinoid recovery fauna after the Late Ordovician mass extinction. Hiiumaacrinus vinni n. gen. n. sp., Protaxocrinus estoniensis n. sp., Eomyelodactylus sp., calceocrinids, and five holdfast types are reported here. Although the fauna has relatively few taxa, it is among the most diverse Rhuddanian faunas known. Similar to other Rhuddanian crinoid faunas elsewhere, the Hilliste crinoid fauna contains crinoids belonging the Dimerocrinitidae, Taxocrinidae, Calceocrinidae, and Myelodactylidae; most elements of the new fauna are quite small, perhaps indicative of the Lilliput Effect. [ABSTRACT FROM AUTHOR]

The Actinocrinitidae were among the most abundant crinoids worldwide during the Lower Mississippian. Recent systematic revisions of the family allow a revised genus- and species-level understanding of these crinoids globally and a more precise means by which to understand the temporal and facies distribution of genera and species in this important Mississippian family. Two genera with a total of five species of Actinocrinitidae (and five additional forms left in open nomenclature) are recognized from the Fort Payne Formation, including Actinocrinites jugosus (Hall, 1859), Actinocrinites spp. indeterminate, Thinocrinus gibsoni (Miller and Gurley, 1893), Thinocrinus lowei (Hall, 1858), Thinocrinus probolos (Ausich and Kammer, 1991), Thinocrinus akanthos new species, Thinocrinus sp. aff. T. gibsoni, Thinocrinus spp. indeterminate, and two taxa recognized as only Actinocrinitidae genus and species indeterminate. Actinocrinites tripus Ehlers and Kesling, 1963 is recognized as a junior synonym of Thinocrinus gibsoni. Thinocrinus, rather than Actinocrinites as previously thought, is the dominant Fort Payne Formation actinocrinitid. Fort Payne Formation carbonate buildup facies (wackestone buildups and crinoidal packstone buildups) each have characteristic species of Thinocrinus. Actinocrinites is relatively rare in the Fort Payne Formation, but occurs preferentially in crinoidal packstone buildups. [ABSTRACT FROM AUTHOR]

The adoral surface of a crinoid theca has traditionally been called the tegmen, despite a wide range of morphologies; and, unfortunately, this has obscured the potential to recognize homologies between blastozoans and crinoids. With present recognition of these homologies, the constructional morphology of crinoid oral regions is explored, herein. Two major types of oral regions exist among crinoids: (1) an oral surface with the mouth exposed; and (2) a tegmen, in a restricted definition, with the mouth covered beneath solid plating. A tegmen is constructed by exaptation of oral surface plating and, commonly, other thecal plating. A pseudo-tegmen is an exaptation of aboral cup plates (i.e., radial plates). Tegmens or pseudo-tegmens evolved in all major crinoid clades at least once as an exaptation of oral surface plating. Tegmens evolved iteratively both between and within clades. In some cases, tegmen plates can be homologized with oral surface plates, but in other cases this is not apparent. Examples of tegmens that evolved many times include tegmens with an appearance of oral surface plates cemented in place; tegmens with fixed ambulacral cover plates and primary peristomial cover plates disproportionately enlarged; tegmens composed exclusively, or nearly so, of greatly enlarged primary peristomial cover plates; tegmens with tessellate plating but presumably with some flexibility; and tegmens constructed of innumerable undifferentiated plates. Most tegmens have all ambulacral cover plates fixed; but in some instances, the abaxial ambulacral cover plates remain moveable. Additionally, some lineages that possessed a tegmen evolved an oral surface secondarily, likely as an atavism. Based on this restricted definition of a tegmen, the hemicosmitid blastozoan Caryocrinites also evolved a tegmen. As known, tegmens dominated among camerate crinoids; and oral surfaces were more common among cladids, hybocrinids, disparids, flexibles, and articulates. However, oral surfaces evolved in some camerate lineages; tegmens evolved in some cladid, disparid, and articulate lineages; and pseudo-tegmens evolved in some flexible and articulate lineages. The iterative evolution of tegmens in crinoids and blastozoans is thought to be an adaptive response to cover the mouth and proximal ambulacra to protect this portion of the digestive tract from predation, scavenging, parasites, and disease causing agents. [ABSTRACT FROM AUTHOR]

Isolation of organic molecules directly from Paleozoic to Cenozoic fossils has been documented, which raises important, new questions about the conditions of preservation and the range of paleobiological issues that can be addressed with these new data. Herein, molecules are isolated from fossil echinoderms exceeding 445 Ma in age. Previously, morphological data have been insufficient to establish a consensus regarding early echinoderm evolution. Thus, organic molecules extracted from fossil echinoderm specimens (mostly Paleozoic) belonging to the classes Asteroidea, Blastoidea, Crinoidea, Diploporita, Echinoidea, and Edrioasteroidea are used to assess the position of crinoids and blastozoans within competing echinoderm phylogenetic hypotheses. Fluorescence excitation-emission spectroscopy of organic molecules in fossil extracts are used to compare relationships among hypotheses. These new data support the hypothesis that living eleutherozoans diverged early from stemmed echinoderms, crinoids are nested within the clade that includes other blastozoans, and edrioasteroids are a distinct clade. [ABSTRACT FROM AUTHOR]

Paleozoic echinoids are exceptionally rare, and little is known of their paleoenvironmental distribution. The echinoid fauna of the Fort Payne Formation (Late Osagean, Early Viséan) of south-central Kentucky is documented. Four genera, ?Archaeocidaris, Lepidocidaris, ?Lepidesthes, and an unidentified lepidocentrid, were recovered and represent three different families. This fauna, and their associated paleoenvironments, give important new insights into the facies distribution of Paleozoic echinoids and the taphonomic biases that affect this distribution. Lepidocidaris is known from the green shale facies, which comprises the core of Fort Payne’s carbonate buildups. ?Archaeocidaris and the lepidocentrid are known from the wackestone buildups and crinoidal packstone buildups. ?Lepidesthes is also known from crinoidal packstone and wackestone buildups, which argues against a semi-infaunal life mode for this taxon. All relatively semiarticulated echinoids were known from autochthonous facies, whereas the only echinoids from the allochthonous facies were disarticulated hemipyramids. Furthermore, deeper-water carbonate buildups were apparently capable of supporting diverse echinoid faunas during the Viséan. [ABSTRACT FROM AUTHOR]

A new crinoid association reported from the Kope Formation (Katian, Ordovician) of northern Kentucky and southwestern Ohio changes the model for facies distribution of crinoids along an Ordovician onshore-offshore depth gradient. Glyptocrinus nodosus n. sp., Plicodendrocrinus casei (Meek, 1871), Cincinnaticrinus varibrachialis (Warn and Strimple, 1977), and Ectenocrinus simplex (Hall, 1847) are reported from a suspension-feeding assemblage with 26 taxa. This assemblage developed above an argillaceous packstone with most of the fossils preserved in shale. The fauna was comprised principally of secondary epifaunally tiered suspension feeders, deposit feeders, and predators. This is the first reported occurrence of Glyptocrinus Hall, 1847 and Plicodendrocrinus Brower, 1995 from the Kope Formation (lower Cincinnatian), and Glyptocrinus is represented by a new species, G. nodosus. Also, this is the first report of pinnulate camerate crinoids from the deep-water facies of the Kope Formation. Thus, deep-water Cincinnatian crinoid assemblages were comprised of disparids, cladids, and camerates; and the assemblage was characterized by a variety of filtration fan types for acquisition of resources. [ABSTRACT FROM AUTHOR]

Phylogenetic relationships among early crinoids are evaluated by maximizing parsimonious-informative characters that are unordered and unweighted. Primarily Tremadocian- Darriwilian ( Early- Middle Ordovician) taxa are analysed. Stratigraphic congruence metrics support the best phylogenetic hypothesis derived using parsimony methods. This study confirms the traditionally recognized lineages of Palaeozoic crinoids and provides new information on the branching order of evolving lineages. Camerates are basal crinoids with progressively more tipward groups (from an Ordovician perspective) being protocrinoids, cladids (paraphyletic), hybocrinids and disparids. The Protocrinoida should be maintained, but the Aethocrinida should be placed within the Cladida. The results of this study identify phylogenetic structure amongst the major early crinoid lineages and delineate the relative positions of crinoid higher taxa along a tree. Each valid higher taxon discussed herein requires a comprehensive treatment to delimit within-lineage phylogenetic relationships. [ABSTRACT FROM AUTHOR]

All known occurrences of crinoids in the Ordovician of France (Armorican Massif, Montagne Noire, Corbières and Pyrénées) are reviewed and replaced stratigraphically. Fully articulated crinoids are described for the first time in the Darriwilian (Middle Ordovician) of the Armorican Massif. The disparid crinoid Heviacrinus melendezi is reported from the middle and late Darriwilian ( artus and teretiusculus zones) of both Brittany and Normandy, which extends both its geographic distribution and its temporal range. In addition, a new species of Heviacrinus , H. tromelini is described from the late Darriwilian ( teretiusculus zone) of both Brittany and Normandy. Finally, three successive French Ordovician crinoid faunas are identified. They show strong palaeobiogeographic affinities with other Gondwanan and peri-Gondwanan assemblages, and in particular with those of the Mediterranean Province. [ABSTRACT FROM AUTHOR]

The Cincinnatian (Katian) of the Cincinnati Tri-State area is widely regarded as one of the most fossiliferous sections known (Meyer and Davis, 2009). Echinoderms from these strata include well-described asteroids, crinoids, cyclocystoids, edrioasteroids, glyptocystoids, mitrates, and ophiuroids. John Pope discovered a partially articulated echinoderm in float from the Fairview Formation that does not correspond to any known Cincinnatian echinoderm. Although mentioned in Ubaghs (1966, as a presumable personal communication from Pope, 1960), Haude and Langenstrassen (1976), Reich (2001), and Reich and Haude (2004), this specimen at the Cincinnati Museum Center (CMCPIP 51316) has neither been described nor illustrated; yet, these authors attributed it to Volchovia Hecker, 1938 in the Class Ophiocistioidea. Questions swirl around this fossil: what is its complete morphology; does it belong to Volchovia; whether or not it can be assigned to Volchovia, is it an ophiocistioid? The first step to understand this enigmatic echinoderm is to illustrate and describe the specimen, which is the objective of this note. [ABSTRACT FROM AUTHOR]

An echinoderm association is reported from the ?early late Albian Paddy Member of the Peace River Formation of British Columbia, Canada. The association includes Frasericrinus mauricensis gen. et sp. nov., two additional distinctive crinoid column types, a poorly preserved asteroid, and an umbilical fragment of the cephalopod Stelckiceras. This is the first report of a Cretaceous isocrinid from North America. The echinoderm fossils are from the top of a succession of storm-deposited sandstones and mudstones (Boulder Creek Formation) that can be correlated southward into nearshore and terrestrial facies of the Paddy Member of the Peace River Formation. The echinoderm fossils were buried (and probably lived) about 12-14 km from the contemporaneous shoreline in an estimated water depth of 10-20 m. Integration of biostratigraphic and allostratigraphic schemes suggests that the echinoderms are of earliest late Albian age. The association of the echinoderm fauna with ammonites of Boreal affinity indicates deposition in northern waters, although the presence of Tethyan inoceramids in apparently coeval Paddy Member strata 270 km to the east suggests that northward-advancing water from the Gulf of Mexico had reached northwestern Alberta, if not actually merged with the Boreal embayment. The nearshore occurrence of Cretaceous stalked crinoids is indicative of an asynchronous, gradual migration of stalked crinoids to deep-water habitats, to which they are restricted in modern oceans. [ABSTRACT FROM AUTHOR]

A new echinoderm fauna is reported from the Brassfield Formation (Rhuddanian, Silurian) of Bath County, Kentucky. The Brassfield Formation was the first extensive marine unit to be deposited following the end-Ordovician glaciation and extinctions and represents several shallow, open-marine facies. These facies supported a diverse pelmatozoan fauna. This report not only extends the geographic distribution of this fauna, but also the temporal range of the fauna back to Rhuddanian time. Six pelmatozoans are reported, including the crinoids Browerocrinus arthrikos n. gen. n. sp., Temnocrinus americanus n. sp., Stereoaster sp., and Dendrocrinus sp.; and the glyptocystitids Brockocystis nodosarius Foerste, 1919, and Anartiocystis whitei Sumrall, 2002. In addition, the asteroid Gordonaster brassfieldensis Blake and Ettensohn, 2009, was reported previously from this locality. Browerocrinus increases the diverse calceocrinid fauna from the Brassfield Formation; Temnocrinus was previously only known from the Homerian (Silurian) of England; and this is the first known occurrence of Stereoaster beyond the greater Dayton, Ohio, region. Furthermore, this is the first Brassfield locality known with two glyptocystitid taxa. [ABSTRACT FROM AUTHOR]

Study of new collections of the Wenlock and Pridoli, Silurian, crinoids from Saaremaa, western Estonia, result in taxonomic revision, expanded ranges, and new taxa. Eucalyptocrinites regularis and Periechocrinus laevis are recognized outside of Sweden for the first time. Desmidocrinus laevigatus Ausich et al., 2012 is reassigned to Methabocrinus. Because the type species of Methabocrinus was previously known only from glacial sediments, the age and provenance of this genus are constrained for the first time. A new crotalocrinitid, Velocrinus coniculus new genus and species, is described. Although the Pridoli faunas of western Estonia contain only twelve species-level taxa assigned to nine genera, this fauna is one of the four richest Pridoli faunas known. [ABSTRACT FROM AUTHOR]

The family Actinocrinitidae was a significant contributor to the global biodiversity peak of crinoids that occurred during the Mississippian and is referred to as the “Age of Crinoids.” Although the actinocrinitids are a major component of that high diversity, they are also a source of much taxonomic confusion. Previously, generic concepts were not applied equally between Europe and North America creating disparity in the definition of genera. In this contribution, all genera are defined objectively by discrete characters, and the generic assignments of all species are reevaluated. Twenty genera are described. A total of 206 species were evaluated of which 56 species and one taxon in open nomenclature are reassigned to different genera, 21 species are designated as nomina dubia, and three species and one genus are now incertae sedis.A phylogenetic hypothesis is presented for the relationships of the genera of Actinocrinitidae genera based on a parsimony-based analysis and plotted against stratigraphic ranges. Although groupings were revealed in this analysis, the Actinocrinitidae cannot be readily subdivided into subfamilies. Rapid diversification occurred during the Tournaisian following the Hangenberg Extinction of probable fish predators. The late Devonian (Famennian) occurrence of the highly derived genera Abactinocrinus and Physetocrinus suggests there is a more extensive, but undocumented, evolutionary history for the Actinocrinitidae during the Devonian. [ABSTRACT FROM AUTHOR]

The Mississippian Fort Payne Formation of Kentucky, Tennessee, and Alabama is well known for its abundant crinoids and a diverse array of autochthonous and allochthonous carbonate and siliciclastic facies. Using Principal Coordinate Analysis and Non-Metric Multidimensional Scaling, it is demonstrated that distinct, contemporaneous, and geographically adjacent autochthonous facies in south-central Kentucky supported distinct crinoid assemblages. The two carbonate buildup facies had different assemblages dominated by camerate crinoids, carbonate channel-fill deposits were dominated by advanced cladid crinoids and the camerate Elegantocrinus hemisphaericus, and green shale facies supported a fauna dominated by disparids and primitive cladid crinoids. Allochthonous facies contain neither distinctive nor exotic taxa. Thus, these transported assemblages are considered a mixture of elements from the recognized, autochthonous facies. Faunal assemblages from Dale Hollow Reservoir are allochthonous; and faunas in north-central Alabama and south-central Tennessee are different from others, which may reflect slight biogeographic distinctions. [ABSTRACT FROM AUTHOR]

Fossilized tube feet are described on Codiacrinus schultzei Follmann from the Lower Devonian Hunsrück Slate of Germany. This is the first definitive proof of tube feet on any fossil crinoid. Three lightly pyritized, flattened tube feet are preserved in a single interray of this cladid crinoid. The tube feet were at least 7 mm long. Their preservation is very similar to the tube feet reported previously from a Hunsrück ophiuroid, except that the Codiacrinus tube feet have small papillae, similar to living crinoids. [ABSTRACT FROM AUTHOR]

The biodiversity and biogeography of 217 genera of Mississippian crinoids from North America and the British Isles shed light on the macroevolutionary turnover between the Middle Palaeozoic and Late Palaeozoic Crinoid Evolutionary Faunas. This turnover resulted from steady differential extinction among clades during the middle Mississippian after crinoids reached their Phanerozoic peak of generic richness during the early Mississippian. This peak richness was primarily a function of Mississippian originations rather than Devonian-holdover taxa. North America had 100 per cent higher generic richness than the British Isles, but rarefaction analysis adjusts the difference to only 37 per cent higher. Rarefaction demonstrated that North America had increased biodiversity, compared to the British Isles, almost entirely among monobathrid camerates, disparids and primitive cladids. In contrast, diplobathrid camerates, advanced cladids and flexibles had the same generic biodiversity between regions, when compared using rarefaction. The early Mississippian radiation resulted from two primary causes: (1) the expansion of Tournaisian carbonate ramps following the Frasnian mass extinction of reef faunas and (2) the predatory release in the Tournaisian following the end-Famennian Hangenberg extinction of durophagous fishes. A majority of crinoid genera from the British Isles are cosmopolitan. When combined with rarefaction analysis and evidence for more first occurrences in North America, this suggests higher origination rates in North America, especially when carbonate ramps were widespread. With the gradual reduction in the area of carbonate ramps from the early to late Mississippian, in conjunction with the radiation of new durophagous fishes, camerate crinoids in particular experienced continuous background extinction, without replacement, beginning during the earliest Viséan (late Osagean). By middle Viséan time (late Meramecian) advanced cladids were dominant in all settings. This resulted in the transition from the Middle Palaeozoic to the Late Palaeozoic Crinoid Macroevolutionary Fauna. [ABSTRACT FROM AUTHOR]

Biomarkers and other ancient preserved molecules are rapidly being discovered and used to study the evolution of life on Earth. We report the existence of echinoderm-specific organic molecules from different lower Mississippian (340 Ma) crinoid species that occur in the same sedimentary bed. These are the oldest examples of biomarker molecules extracted directly from fossilized remains. These biomarker molecules appear to resemble aromatic or polyaromatic quinones, based upon ultraviolet and visible light spectroscopy, fluorescence excitation-emission matrix spectroscopy, and electrospray ionization time-of-fiight mass spectrometry. Results suggest that the preservation of diagnostic organic molecules is much more common that previously realized, and that preserved organic molecules may provide an independent method to unravel phylogenetic relationships among echinoderms and, perhaps, other fossilized organisms. [ABSTRACT FROM AUTHOR]

New crinoid and blastoid faunas are reported from the Fort Payne Chert of northcentral Alabama and the Fort Payne Formation of south-central Tennessee, including 27 crinoid and three blastoid species. One new species, Magnuscrinus kammeri, is described. Based on a nearly identical fauna in southcentral Kentucky, the Fort Payne Formation in north-central Alabama and south-central Tennessee is late Osagean (early Viséan; Mississippian time bin 6). Thus, throughout the outcrop belt from south-central Kentucky to north-central Alabama, the age is the same. This indicates that the strike of the prograding Fort Payne Chert and Formation was approximately coincident with the present-day outcrop belt. [ABSTRACT FROM AUTHOR]

Crinoid faunas from the Lower Devonian of South America are poorly known. Two new taxa are described from the Emsian Ida Formation at Cerro Kochis in the Cochabamba Department: the rhodocrinitid, Lutocrinus boliviaensis n. gen. n. sp. and Griphocrinus pirovanoi n. sp. Two additional camerates are reported from the Emsian Belèn Formation of the Altiplano region in the La Paz Department, including Ctenocrinus branisai n. sp. and Boliviacrinus isaacsoni Mcintosh, 1988. In addition, a specimen of the blastoid, Pachyblastus dicki Bremier and Macurda, 1972, was recovered from the Altiplano region. These crinoids and material previously collected by Leonardo Branisa, including specimens of C. branisai n. sp., Apurocrinus sucrei Mcintosh, 1981, B. isaacsoni Mcintosh, 1988, and L. boliviaensis n. sp., are described and revised. The specimens give new insights into the Lower Devonian Malvinokaffric Realm of Bolivia, a relatively new frontier in crinoid paleontology. [ABSTRACT FROM AUTHOR]

Abstract: The end-Katian (Late Ordovician) crinoid mass extinction triggered the change from the Early to the Middle Paleozoic crinoid evolutionary faunas (CEFs). This was a change from diplobathrid camerate-disparid-hybocrinid dominated faunas to faunas dominated by monobathrid camerate, cladid, and flexible crinoids. All clades suffered extinctions at the end-Katian event, but diplobathrid camerates, disparids, and hybocrinids suffered higher rates of extinction. The primary amount of diversification occurred in clades that would become dominant during the Silurian. However, the formation of the characteristic Middle Paleozoic CEF was protracted beyond the Late Ordovician extinction event. Monobathrid camerates and flexibles diversified through the Llandovery, but both dendrocrinid and cyathocrinid cladids did not diversify until later. Monobathrid camerate genera and families diversified, the flexible diversification was largely at the genus level, cyathocrine diversification was largely among families, and dendrocrinids did not diversify significantly until after the Llandovery. Overall disparity decreased during the end-Katian extinction by reducing the disparity within each clade. Disparity remained fairly constant during the Hirnantian but increased significantly during the Llandovery by both increasing disparity within clades and expanding the morphospace of the disparids due to the radiation of families with new morphologies. North America was the biogeographic center of origination for the families that survived to become dominant Silurian clades. [Copyright &y& Elsevier]

A very early juvenile specimen of Hypselocrinus hoveyi with arms and partial column attached is utilized to examine the growth in this Mississippian advanced cladid crinoid. The aboral cup height of this specimen is 4 mm. In contrast to results reported in previous studies of crinoids, Hypselocrinus hoveyi grew with a combination of allometric and isometric growth. Different plates of the aboral cup grew with a combination of growth modes, and arms grew with allometric growth or relative change in shape that was not strict allometry. [ABSTRACT FROM AUTHOR]

A new species of Apiocrinites is described from the Middle Jurassic (Callovian) Matmor Formation of the Negev, Israel. Apiocrinites negevensis is from the tropical latitudes in the Tethys, in contrast to all other reported species of this genus. With a narrow radial facet and adjacent arms not in lateral contact and large aboral cup plates, A. negevensis is quite unusual for this genus. [ABSTRACT FROM AUTHOR]

The Silurian crinoids of Estonia are re-evaluated based on new collections and museum holdings. Nineteen species-level crinoid taxa are now recognized. All crinoid names applied to Estonian Silurian crinoids during the middle 19th century are disregarded. Especially significant is the fauna reported herein from the Pridoli because coeval crinoids are very poorly known from the Baltic region and elsewhere. One new genus and four new species are described from Estonia, namely Calceocrinus balticensis sp. nov., Desmidocrinus laevigatus sp. nov., Eucalyptocrinites tumidus sp. nov., and Saaremaacrinus estoniensis gen. et sp. nov. [ABSTRACT FROM AUTHOR]

Crinoids were first reported from the Cuyahoga Formation in northeastern Ohio by James Hall in 1863. However, these crinoids have not been re-examined in detail since the late nineteenth century. With the restudy of classical and more recent collections, ten (nine camerate and one disparid) species-level taxa are recognized from the late Kinderhookian Meadville Shale Member, Cuyahoga Formation, including the camerates Amphoracrinus viminalis (Hall, 1863); Aorocrinus helice Hall, 1863; Aorocrinus meyeri n. sp.; Aryballocrinus martini n. sp.; Cusacrinus daphne (Hall, 1863); Platycrinites s.l. contritus (Hall, 1863); Platycrinites s.l. graphicus (Hall, 1863); Platycrinites s.l. lodensis (Hall and Whitfield, 1875); and Platycrinites s.l. burkei n. sp. In addition, Halysiocrinus sp. is the first disparid reported from this fauna. Platycrinites s.l. bedfordensis (Hall and Whitfield, 1875) is designated a nomen dubium. Growth is evaluated for Aorocrinus helice and Cusacrinus daphne, which had contrasting development. The growth of the Aorocrinus helice calyx was largely not allometric but that of the primaxil plate was, suggesting the arms may have grown allometrically. In contrast, much of the calyx of Cusacrinus daphne displayed allometric growth. [ABSTRACT FROM AUTHOR]

The article focuses on the awarding of the 2010 Paleontological Society Medal to Stig Magnus Bergström. It states that Bergström received his undergraduate and graduate degrees from Lund University in Sweden, and was first associated with Ohio as a Fulbright Scholar in the academic year 1960-1961. It says that Bergström also received recognitions from the Ohio State University and Hadding Prize for his works on and teaching of paleontology.

Fossil echinoderms are a rich source of information concerning biotic interactions. In this study we analyzed the premortem encrustation of the highly specialized Middle Devonian rugose corals Aspasmophyllum crinophilum and ?"Adradosia" sp. on camerate crinoid stems. Aspasmophyllum infested living crinoid stems by sclerenchymal outgrowth that formed a skeletal ring but ?"Adradosia" sp. encrusted the stems rapidly, without building a ring. These coral-crinoid biocoenoses indicate a settlement advantage for the rugose corals within densely populated communities of the lower Givetian. The corals could be interpreted as large epizoozoans that benefited as secondary tierers reaching relatively high tiering levels. It also suggests the ability for the affected crinoids to repel the coral by overgrowing the corallite with a local increased stereomic growth. Because the crinoid axial canals are not penetrated, the corals cannot be considered as predators or parasites of crinoids. Therefore, the described biocoenosis is interpreted as commensalism. The species A. crinophiluni is redescribed, and a neotype is defined, because of the loss of the initial types. Two types of ichnofossils can be attributed to the premortem encrustation of both corals. They are described as Ostiocavichnus n. ichnogen. and are attributed to the stereomic response of the infested hosts. These swellings are characterized as either elliptical (Ostiocavichnus ovalis n. ichnogen. n. ichnosp. due to the assumed reaction of A. crinophilum) or subcircular concavities (O. rotundatus n. ichnogen. n. ichnosp. due to the reaction of ?"Adradosia sp."). [ABSTRACT FROM AUTHOR]