<i>Celticystis</i>n. gen., a gomphocystitid cystoid from the Silurian of Sweden

Bockelie, Johan Fredrik

doi:10.1080/11035897909452575

Cited by 9 publications

(9 citation statements)

References 3 publications

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“…Blastozoa of the second cited group commonly do have a fixed plate arrangement immediately peripheral to the peristome, often a single circlet with a smaller number of plates than succeeding, less regularly arranged circlets. This is especially evident in the Diploporita (circumorals of Sphaeronitidae and Gomphocystitidae, periorals of Holocystitidae; see Paul 1971Paul , 1973Bockelie 1979) and Paracrinoidea (peristomals of both Platycystitida and comarocystitids (see Parsley 1978Parsley , 1980Frest and Strimple 1982); the same arrangement is also present in several platycystitid genera (Frest research in progress)). The degree of differentiation of the so-called oral surface varies greatly among genera.…”

Section: The Eocrinoid Tegmenmentioning

confidence: 76%

Ampheristocystis, a Silurian (Lower Wenlock) eocrinoid (Echinodermata, Blastozoa) from Indiana

Frest

2005

Geological Journal

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The enigmatic blastozoan echinoderm Ampheristocystis concentricus, based on four specimens from the upper part of the Osgood Member, Salamonie Dolomite (Upper? Llandovery-Lower Wenlock), southeastern Indiana, is most likely an eocrinoid. Supporting this assignment are the five basals(?), five symmetrical appendage facets (possibly bearing biserial brachiolar trunks) and details of the thecal plating (moderate number of semiregularly arranged thecal plates). Some features (poorly known subvective appendages and poreless thecal plates) could indicate paracrinoid affinities, and suggest that the classes Eocrinoidea and Paracrinoidea may be more closely related than indicated by current taxonomy. Whatever the class disposition, the genus is the youngest representative yet known. Placement in the Blastozoa, based on holoperipheral plate growth, morphology of the brachiole-like appendages and peristome, among other features, is unequivocal. The sharply discriminated oral and thecal plating, and protuberant anal opening, are unusual features for either paracrinoids or eocrinoids. Separate familial status is advocated for Ampheristocystis, but the family is not assigned to an order. The oral surface of the genus, consisting of regular orals and suborals, and fixed ambulacrals, presents an arrangement unique among eocrinoids, but analogous to the tegmen of camerate crinoids and of the rhombiferan family Caryocrinitidae. Development of a regular tegmen, fairly regular thecal plating and elongate fusiform shape indicate Ampheristocystis is an evolutionarily convergent, aberrant blastozoan, perhaps competitive with the camerates that generally dominated Silurian echinoderm faunas, and with the contemporary, equally successful blastozoan Caryocrinites. Ampheristocystis is not closely associated with hard surfaces or debris piles, as are many Osgood echinoderms, but preferred soft silt or mud bottoms. Associated echinoderms include several diploporites, coronoids, a few large camerates (e.g. Eucalyptocrinites) and Caryocrinites. Two specimens have evidently decollated the stem; one retains a sizeable, crinoid-like stem. Hence, it is presently unclear whether the life habits of this genus were more like that of the common Osgood diploporites or stemmed contemporaries such as Caryocrinites and Eucalyptocrinites. Alternatively, it could perhaps exploit both habits equally well.

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Section: The Eocrinoid Tegmenmentioning

confidence: 76%

Ampheristocystis, a Silurian (Lower Wenlock) eocrinoid (Echinodermata, Blastozoa) from Indiana

Frest

2005

Geological Journal

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“…The peri-orals of Tristomiacystis share ambulacral facets with the first ambulacral plates; those of Bistomiacystis do not. Finally, when ambulacra curve, ambulacral facets are always aligned on the outside of the curve as in the gomphocystitid diploporite Celticystis Bockelie 1979a (Fig. 14.3) and the paracrinoid Bistomiacystis (Fig.…”

Section: Homology Of Oral Platesmentioning

confidence: 99%

“…( 2 ) The protocrinitid diploporite Tristomiacystis Sumrall et al, 2009. ( 3 ) The gomphocystitid diploporite Celticystis Bockelie, 1979a. A–E=ambulacra; An=anus; G=gonopore; H=hydropore; M=mouth; PO1–PO6=peri-oral plates.…”

Section: Homology Of Oral Platesmentioning

confidence: 99%

“…Bockelie (1979a, p. 160, fig. 5a) showed an unexpected arrangement in Celticystis Bockelie, 1979a, in which the first ambulacral facet was shared between a peri-oral and the first ambulacral plate in ambulacra A, B, D, and E, but the first facet was confined to the first ambulacral plate in ambulacrum C. The figure is a partial reconstruction from two specimens, so perhaps one should not read too much into the anomalous ambulacrum C. Another interesting feature of the ambulacra of Celticystis is that over most of the theca the ambulacral plates form part of the thecal wall, but on reaching the basal circlet of plates by which the diploporites were attached to the substrate in life, the ambulacrals lie on top of the 'basals.' The tips of the ambulacra are recumbent (Bockelie, 1979a, p. 161, fig.…”

Section: Ambulacral Structurementioning

confidence: 99%

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Testing for homologies in the axial skeleton of primitive echinoderms

Paul

2017

J. Paleontol.

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Abstract.-The extraxial axial theory is used to investigate homology of ambulacral and oral plating because it predicts terminal branching and terminal addition of plates in the axial skeleton, although exceptions to the former may occur in some Paleozoic echinoderms. The variety of morphological designs and anomalous individuals also provide tests of plate homology. Homology of ambulacra is generally accepted, with the hydropore and/or single gonopore in Carpenter's CD interray. In the 2-1-2 ambulacral pattern the unbranched ambulacrum is always in Carpenter's A ray. All ambulacral morphology requires just three instructions: 'grow,' 'branch,' and 'stop.' The range of variation in echinoderms with fewer than five ambulacra implies that both the 'branch' and 'stop' instructions acted independently in all five rays. Numbers of ambulacra may or may not correlate with numbers of orals. Two basic patterns of 'cystoid' oral plating occur; with a single radial (circum-oral, CO) plate from each ambulacrum plus a sixth in the CD interray, and with all six interradial peri-oral (PO) plates, with two in the CD interambulacrum. Five 'orals' may involve loss of PO3 or PO6. Erect ambulacral structures are lost first in taphonomy and so poorly known. All ambulacral skeletal elements bear the same topological relationship to ambulacral soft tissues. Where branched ambulacra occur, the trunk or flooring plates are often modified first brachiolars or pinnulars. Both brachioles and pinnules may arise from facets developed on one or two flooring plates. Terminal addition of plates, spacing of brachioles/pinnules, and lack of musculature to open cover plates all suggest that 'cystoids' had extensions of the water vascular system in their ambulacra.

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“…Gomphocystites occurs slightly earlier than the holocystitids, with the earliest undoubted occurrence in the Llandovery-age Hopkinton dolomite of Iowa (Witzke, 1976) and persists as a common faunal component in strata containing the Holocystites Fauna (which are largely restricted to Wenlock age). Gomphocystites also has a greater biogeographic range than holocystitids, with fossils known from New York, USA (Brett, 1985a), and the Baltic Celtacystis (Gomphocystites) gotlandicus (Angelin, 1878), which has been proposed to be very closely related to Gomphocystites (Bockelie, 1979(Bockelie, , 1984. The morphology of Gomphocystites deviates (3) O1-O6 have been disarticulated, giving the appearance of a greatly enlarged peristomial opening being bordered by the facetal plate circlet.…”

Section: Holocystitid Plate Morphologiesmentioning

confidence: 99%

Generic revision of the Holocystitidae of North America (Diploporita, Echinodermata) based on universal elemental homology

Sheffield¹,

Sumrall²

2017

J. Paleontol.

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Abstract.-The Holocystites Fauna is an enigmatic group of North American diploporitans that presents a rare window into unusual middle Silurian echinoderm communities. Multiple systematic revisions have subdivided holocystitids on the basis of presumed differences in oral area plating and respiratory structures. However, these differences were based on a fundamental misunderstanding of the homologous elements of the oral area and the taphonomic process; taphonomic disarticulation of the oral area formed the basis for the erection of Pentacystis and Osgoodicystis as separate genera, and Osgoodicystis is interpreted as the junior synonym of Pentacystis. Holocystitids show a conservative peristomial bordering plate pattern that is shared among all described genera. The peristome is bordered by seven interradially positioned oral plates as is typical for oral plate-bearing blastozoans. A second open circlet of facetal plates lies distal to the oral plates; five of these facetal plates bear facets for feeding appendages (lost on the A ambulacrum in some taxa), while two lateral facets (present in all taxa except Pustulocystis) do not. Holocystitid taxa show minor modifications to this basic peristomial bordering plate pattern. As thecal morphologies are highly variable within populations, taxonomic revision of holocystitids is based on modifications of the plating of the oral area.

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Celticystisn. gen., a gomphocystitid cystoid from the Silurian of Sweden

Cited by 9 publications

References 3 publications

Ampheristocystis, a Silurian (Lower Wenlock) eocrinoid (Echinodermata, Blastozoa) from Indiana

Ampheristocystis, a Silurian (Lower Wenlock) eocrinoid (Echinodermata, Blastozoa) from Indiana

Testing for homologies in the axial skeleton of primitive echinoderms

Generic revision of the Holocystitidae of North America (Diploporita, Echinodermata) based on universal elemental homology

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