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Rheocrinus
Taxonomy
Rheocrinus was named by Haugh (1979) [Sepkoski's age data: O Ashg]. Its type is Rheocrinus aduncus.
It was assigned to Anthracocrinidae by Haugh (1979); and to Diplobathrida by Sepkoski (2002).
It was assigned to Anthracocrinidae by Haugh (1979); and to Diplobathrida by Sepkoski (2002).
Species
R. aduncus (type species)
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If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.
Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| B.N. Haugh 1979 | An "anthracocrinid" with a low subconical dorsal cup. Median ray ridges very faintly developed on slightly elevated ray taxis. No median interray ridges in any of the interrays. Sutures distinct and moderately depressed, especially near the plate corners. Plate surfaces smooth, unornamented. Lower dorsal cup border distinctively crenulate due to dorsally projecting, spade-shaped radials alternating with withdrawn trapezoidal basals intercalated in the same lowest plate "bicirclet." Infrabasals completely hidden in a basal invagination. Interrays all of equal width. Posterior interray distinguished by a single large primanal followed by a single large interbrachial (anal) plate; remaining higher order posterior interbrachial plates small, irregular polygonal, and variable in number from specimen to specimen. Lateral interrays consisting of a large first interbrachial whose lower corners only, contact the radials, followed by two subequal medium-sized interbrachials, the latter followed by several smaller interbrachials, variable in number among interrays, and not continuing onto the tegmen. All upper interradial spaces filled by fixed pinnules that "bridge" the lower interbrachials. Free arms proximally cuneate uniserial, distally biserial, unbranched, densely pinnulate, four arms per ray. Tegmen highly doomed, plate pattern and precise position of anal vent unknown. Stem large and pentameral proximally, tapering to a smaller diameter with round cross section medially, distal region expanded into a club-shaped, radicle- bearing radix with pentagonal cross section. |
Measurements
No measurements are available
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| Source: o = order, c = class, p = phylum | |||||
| References: Aberhan 1992, Kiessling 2004, Aberhan et al. 2004 | |||||
Age range: Richmondian or 449.60000 to 445.50000 Ma
Collections: one only
| Time interval | Ma | Country or state | Original ID and collection number |
|---|---|---|---|
| Richmondian | Canada (Ontario) | R. aduncus (201745) |