Crinoids of the Champlainian (Middle Ordovician) Guttenberg Formation—upper Mississippi Valley region

Kolata, Dennis R.

doi:10.1017/s002233600002223x

Cited by 28 publications

(75 citation statements)

References 2 publications

(5 reference statements)

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“…The unusual aspect of these fossils and the contrasted interpretations of the aulacophore as equivalent to a pelmatozoan stem (e.g. Philip 1979;Kolata et al 1991), a feeding arm (e.g. Ubaghs 1961b;, or even to a chordate tail (e.g.…”

Section: S T Y L O P H O R a N Smentioning

confidence: 95%

“…Kirk 1911;Caster 1952;Gill and Caster 1960;Caster et al 1961;Jefferies 1968Jefferies , 1984Jefferies , 1986Philip 1981;Kolata and Jollie 1982;Frest 1988;Kolata et al 1991;Woods and Jefferies 1992;Cripps and Daley 1994;Sutcliffe et al 2000;Gee 2000). Finally, an infaunal mode of life has been suggested for several mitrates possessing a theca with ratchet sculpture (cuesta-shaped ribs, asymmetrical tubercles), by analogy with other similarly ornamented organisms (Jefferies and Prokop 1972;Jefferies and Lewis 1978;Jefferies 1982Jefferies , 1984Jefferies , 1986Jefferies , 1999Kolata and Jollie 1982;Savazzi et al 1982;Kolata et al 1991;Ruta 1997b;Ruta and Theron 1997;Ruta and Bartels 1998;Sutcliffe et al 2000).…”

Section: S T Y L O P H O R a N Smentioning

confidence: 99%

“…Most authors consider that the proximal aulacophore cavity housed powerful muscles (e.g. Jaekel 1918;Jefferies 1968;Philip 1979;Ubaghs 1981;Kolata and Jollie 1982;.…”

Section: S T Y L O P H O R a N A N A T O M Ymentioning

confidence: 99%

“…They constitute large¯exible integumentary areas on the lower thecal surface (`infracentral areas') and on the upper surface (`supracentral area'), enclosed by the rigid marginal frame. On the lower surface of stylophorans, an asymmetrical structure (the`zygal bar') resulting from the association and joining of two opposite marginals typically separates a left and a right infracentral areas (Kolata et al 1991;Parsley 1997;Lefebvre et al 1998a;Ruta 1999b). The number of somatic elements increases with growth in most cornutes and several mitrates (e.g.…”

Section: The Thecamentioning

confidence: 99%

“…This ori®ce corresponds to the anus (Bather 1913;Chauvel 1941;Ubaghs 1967a;Kolata and Guensburg 1979;Ruta 1999c;Sumrall and Sprinkle 1999;Lefebvre and Vizcaõ Èno 1999). The anus can open on the upper surface (e.g.…”

Section: The Thecamentioning

confidence: 99%

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Functional Morphology of Stylophoran Echinoderms

Lefèbvre

2003

Palaeontology

134

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ABSTRACT. The life orientation and mode of life of stylophorans are a subject of much ongoing debate. Examination of the ornamentation occurring both on the arm and theca in several cornutes and mitrates strongly supports the view that the life orientation was similar in all stylophorans and was`¯at-surface down'. The presence of an asymmetrical ornamentation adapted to hinder, or minimize, back slippage of the organism in all stylophorans gives strong support to their interpretation as mostly sessile organisms, feeding with the arm facing the current and the theca downstream. The examination of a wide array of thecal morphologies and sculpture patterns displayed by the various groups of cornutes and mitrates allows the identi®cation of three main modes of life in stylophorans: (1) an epibenthic mode of life, with the theca as main anchor to the substrate (e.g. asymmetrical cornutes, Diamphidiocystis); (2) an epibenthic mode of life, with the arm as main anchor to the sediment (e.g. symmetrical cornutes, Peltocystis, primitive Mitrocystitida, some Kirkocystidae); (3) an infaunal mode of life, with the theca buried in a slightly inclined attitude (e.g. some Kirkocystidae, Mitrocystitida with cuesta-shaped ribs). The partially buried mode of life of Lagynocystis is intermediate between 2 and 3.

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Section: S T Y L O P H O R a N Smentioning

confidence: 95%

Section: S T Y L O P H O R a N Smentioning

confidence: 99%

“…Most authors consider that the proximal aulacophore cavity housed powerful muscles (e.g. Jaekel 1918;Jefferies 1968;Philip 1979;Ubaghs 1981;Kolata and Jollie 1982;.…”

Section: S T Y L O P H O R a N A N A T O M Ymentioning

confidence: 99%

Section: The Thecamentioning

confidence: 99%

Section: The Thecamentioning

confidence: 99%

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Functional Morphology of Stylophoran Echinoderms

Lefèbvre

2003

Palaeontology

134

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The pre‐radial history of echinoderms

2005

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Gene sequence data now identify a robust phylogeny of deuterostomes and provide a framework within which the evolution of echinoderms can be interpreted. The topology of the molecular tree makes a number of important predictions about the morphological characters of the earliest echinoderm at its split from hemichordates: it possessed gill slits (but not a notochord), had a bilaterally symmetrical body plan in the adult and, less certainly, underwent torsion during development. Carpoids, a highly contentious group of extinct deuterostomes with a plated calcite skeleton that have variously been interpreted as stem-and crown-group chordates, stem-group echinoderms or stem-and crown-group echinoderms, display many of these basal characters and provide critical evidence for how the latest common ancestor of hemichordates and echinoderms was transformed into a pentaradiate crown-group echinoderm.Cinctans have a large atrial opening in addition to mouth and anus, and are interpreted as pharyngeal basket feeders. The paired grooves associated with the mouth indicate the presence of a hydrovascular system, but not necessarily one built along the echinoderm plan (that is, derived from just the left hydrocoel). Stylophorans have a bilateral body plan that is externally masked by torsion and possess gills, either unpaired and external, or paired and internal, opening into an atrial cavity. Their bilateral appendage is a locomotory organ, not an ambulacrum, and there is no evidence that stylophorans ever possessed a welldeveloped hydrovascular system homologous to the water vascular system of echinoderms and the tentacles of pterobranch hemichordates. Solutes are the most crownward, having a true echinodermal ambulacral system with a single hydropore and no pharyngeal gill openings.

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Ateleocystites?lansaesp. nov. (Mitrata, Anomalocystitidae) from the Upper Ordovician of South Wales

McDermott¹,

Paul²

2015

Geol. J.

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Ateleocystites? lansae sp. nov. is characterized by an elongate body with short spines that taper relatively rapidly. It has granular plate ornament adorally in addition to cuesta‐like ridges. Ateleocystites? lansae occurs commonly in a 5‐cm‐thick fine‐ to medium‐grained sandstone bed, which was rapidly emplaced and transported fossils from shallower water, within the Upper Ordovician (Katian), Slade and Redhill Beds along the A477 road and in the new quarry above The Old Mill Café, Tenby Road (now C3236), west of Llanddowror, Carmarthenshire. Other specimens are known from Sholeshook, Pembrokeshire. On the convex surface, the Welsh species differs from A. guttenbergensis Kolata and Jollie in having a larger central ‘placocystitid’ plate (C17) in contact with six, not five other plates. In addition, the marginal plates are scarcely visible on the convex surface. Plating on the planar surface agrees well with that of both A. guttenbergensis and the type species, A. huxleyi Billings. The presence of articulated appendages and spines and the lack of sediment fill in the bodies suggest that the new specimens were alive when buried. Ateleocystites? lansae probably lived largely buried in the sediment with the convex surface below and moved with the appendage in front. Copyright © 2015 John Wiley & Sons, Ltd.

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Crinoids of the Champlainian (Middle Ordovician) Guttenberg Formation—upper Mississippi Valley region

Cited by 28 publications

References 2 publications

Functional Morphology of Stylophoran Echinoderms

Functional Morphology of Stylophoran Echinoderms

The pre‐radial history of echinoderms

Ateleocystites?lansaesp. nov. (Mitrata, Anomalocystitidae) from the Upper Ordovician of South Wales

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