XXXIII.—<i>Descriptions of several new Genera and Species of</i> Crinoidea

Austin, Thomas

doi:10.1080/03745484309445290

Cited by 36 publications

(4 citation statements)

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“…Blothrocrinus yazdii has longer infrabasals and a higher conical cup than Blothrocrinus longidactylus (Austin and Austin, 1847) and B. brevidactylus (Austin and Austin, 1843a), the only other species having slight interradial notches. The nearly plenary radial facets result in exceedingly narrow interradial notches and suggest Blothrocrinus yazdii is derived from an amabilicrinid.…”

Section: Lorocrinus Zanguensis New Speciesmentioning

confidence: 90%

A Cladid-Dominated Early Mississippian Crinoid and Conodont Fauna From Kerman Province, Iran and Revision of the Glossocrinids and Rhenocrinids

Webster

Maples

Mawson

et al. 2003

Journal of Paleontology

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Section: Lorocrinus Zanguensis New Speciesmentioning

confidence: 90%

A Cladid-Dominated Early Mississippian Crinoid and Conodont Fauna From Kerman Province, Iran and Revision of the Glossocrinids and Rhenocrinids

Webster

Maples

Mawson

et al. 2003

Journal of Paleontology

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“…The crinoid fauna from the West Angle Bay is age equivalent to the Ivorian‐age crinoids from Hook Head, Ireland (Ausich and Sevastopulo, ). Crinoids associated with H. cymrus from the Black Rock Limestone at West Angle Bay include the camerates Rhodocrinites versimilis (Grenfell, ), Actinocrinites laevissimus Austin and Austin, , Dialutocrinus tessellatus (Phillips, ) and Platycrinites sp. ; the cladids Blothrocrinus longidactylus (Austin and Austin, ) and Holcocrinus smythi (Wright, ); and the flexible Taxocrinus hibernicus (Wright, ) (Ausich and Kammer, ).…”

Section: Discussionmentioning

confidence: 99%

A new crinoid from the Mississippian (Early Carboniferous) of South Pembrokeshire, Wales

Howells

Kammer

2013

Geol. J.

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A new species of cladid crinoid, Hylodecrinus cymrus, is described from the Pembroke Limestone Group (Mississippian, Tournaisian, Courceyan) of West Angle Bay in south Pembrokeshire, Wales. It has a medium bowl‐shaped aboral cup, with strong ridges extending across the basals and radials forming pits at the plate corners. It is most similar to the late Tournaisian H. carinatus (Hall, 1861) of North America but differs in having less strongly cuneate brachials that are longer than wide with more subtle carinae on the aboral side. This specimen represents the first report of this genus from Europe, which most probably migrated from North America. Copyright © 2013 John Wiley & Sons, Ltd.

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“…Silurian monobathrid tegmens are also highly variable. Periechocrinus costatus (Austin and Austin, 1843) (Periechocrinidae, Silurian, Fig. 13.2–13.4) has a tegmen composed of numerous, small, undifferentiated plates.…”

Section: Monobathrid Cameratesmentioning

confidence: 99%

Exaptation of pelmatozoan oral surfaces: constructional pathways in tegmen evolution

Ausich

Kammer

2016

J. Paleontol.

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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 blastozoanCaryocrinitesalso 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.

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XXXIII.—Descriptions of several new Genera and Species of Crinoidea

Cited by 36 publications

References 0 publications

A Cladid-Dominated Early Mississippian Crinoid and Conodont Fauna From Kerman Province, Iran and Revision of the Glossocrinids and Rhenocrinids

A Cladid-Dominated Early Mississippian Crinoid and Conodont Fauna From Kerman Province, Iran and Revision of the Glossocrinids and Rhenocrinids

A new crinoid from the Mississippian (Early Carboniferous) of South Pembrokeshire, Wales

Exaptation of pelmatozoan oral surfaces: constructional pathways in tegmen evolution

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