Merocrinus curtus

Classification
Phylum: Echinodermata
Class: Crinoidea
Order: Cladida
Family: Merocrinidae
Genus: Merocrinus
Species: Merocrinus curtus (Ulrich, 1879)

M.curtus_paleoeco

Taxonomic Details

  • 1879 Dendrocrinus? curtus Ulrich, p. 18, pl. 7, fig. 14.
  • 1883 Merocrinus typus Walcott, p. 3 (adv. pub.).
  • 1884 Merocrinus typus Walcott, p. p. 209, pl. 17, fig. 5.
  • 1886 Merocrirnus curtus Faber, p. 19, pl. 1, fig. 2.
  • 1889 Merocrirnus curtus Miller, p. 262, fig. 367.
  • 1889 Merocrinus typus Miller, p. 262.
  • 1889 Dendrocinus curtus Miller, p. 238.
  • 1883 Merocrinus corroboratus Walcott, p. 4 (adv. pub.).
  • 1889 Merocrinus corroboratus Miller, p. 262.
  • 1915 Merocrirnus curtus Bassler, p. 800.
  • 1915 Merocrinus corroboratus Bassler, p. 800.
  • 1915 Merocrinus typus Bassler, p. 801.
  • 1938 Merocrinus typus Bassler, p. 132.
  • 1943 Merocrinus corroboratus Bassler & Moodey, p. 562.
  • 1943 Merocrinus curtus Bassler & Moodey, p. 562.
  • 1943 Merocrinus typus Bassler & Moodey, p. 562.
  • 1943 Merocrinus typus Moore & Laudon, p. 155, pl. 53, fig. 16.
  • 1944 Merocrinus corroboratus Moore & Laudon, p. 155, pl. 53, fig. 17.
  • 1944 Merocrinus typus Moore & Laudon, p. 155, pl. 53, fig. 16.
  • 1973 Merocrinus corroboratus Webster, p. 174.
  • 2003 Merocrinus corroboratus Webster, online computer access.
  • 2003 Merocrinus curtus Webster, online computer access.
  • 2005 Merocrinus corroboratus Brower, online computer access.
  • 2008 Merocrinus typus Brett et al., p. 31, fig. 2.9.
  • 2009 Merocrinus typus Meyer & Davis, p. 177, figs. 12.5E, 12.10A.
  • Stratigraphic Occurrences

    M. curtus_strat

    Geographic Occurrences

    Map point data provided by iDigBio.

    Stratigraphic Description

    Sequences (Formations)

    • C1 Sequence (Clays Ferry/Kope: Economy/Fulton)

    Identification in Hand Sample

    • Slender, narrow cup and nonpinnulate arms that branch isotomously
    • Brachials are prominent at the superior lateral angle
    • Simple armlets about half as stout as the main arm from which they spring
    • Has a small, solid, discoidal holdfast

    Merocrinus curtus from the Eden Formation of Carrollton, Kentucky (OUIP 111 and OUIP 5)

    Published Description

    Brower (2010):

    • A species of Merocrinus with smooth aboral cup and arm plates. Cup cylindrical with relatively wide base; radials fully in contact, with wide radial facets; infrabasals high and radials short compared to cup height. Arms with relatively wide brachs, especially the proximal ones, compared to most merocrinids; arms with bilateral heterotomy above the primibrachs; highest observed axillary located on quartibrachs; arms with at least eight branches per ray; roughly average numbers of brachs in various parts of arms for genus. Anal sac straight, at least up to proximal tertibrachs.

    Brett (2008):

    • However, a single specimen from the lower Kope, Fulton submember, which is the only source for Merocrinus curtus Ulrich, 1879, has a small, solid, discoidal holdfast cemented to a bryozoan with an intact distal column resembling that of Merocrinus (Fig. 2.9). This single specimen suggests permanent, cemented attachment in M. curtus. Surprisingly, few such holdfasts have been notes in associated with Merocrinus columns; possibly some have been identified as Anomalocrinus Meek and Worthen, 1865.

    Meyer et al. (2002):

    • Cladid with a slender, narrow cup and nonpinnulate arms that branch isotomously (Moore and Teichert, 1978, Fig. 409)/ Cup width does not greatly exceed that of the stalk. Total stalk length is unknown, although a stalk measuring more than 60 cm without crown or termination was found in the lower Kope Formation at Duck Creek near the k445 section.

    Bather (1896):

    • All known species of Iocrinus further resemble one another in the marked incrication of the brachials; while the species of Merocrinus have as a simple rule smooth brachials, although M. curtus, as figured and described by Ulrich (“Dendocrinus curtus,” Journ. Cincinnati Soc. Nat. Hist., II, p. 18 pl. vii, fig. 14, 1879), has brachials “prominent at the superior lateral angle.” The very slight development of this feature in the Mincop specimen is therefore characteristic of Merocrinus rather than of Iocrinus.
    • From Merocrinus curtus specimen A is clearly distinguished by the regular dichotomy of its arms, for in M. curtus there are simple armlets, “about half as stout as the main arm from which they spring.” The cup is also lower in M. curtus.