Articulata

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CRINOIDEA
Taxonomy Phylogeny

Phylum: Echinodermata
Subphylum: Crinozoa
Class: CRINOIDEA

o Echinodermata
`--+--Echmatocrinus brachiatus
   `--o Crinoidea
      |--Aethocrinida
      `--+--Disparida
         `--+--Camerata
            `--Cladida (incl. Flexibilia and Articulata)


Articulata
Ptilometra australis, the Passion Flower feather star, a modern crinoid (Articulata, Comatulida, Tropiometracea, Ptilometridae,)

Contents

Introduction

Age: Carboniferous to Recent (see below).

Description: (from Weinberg Rasmussen, 1978) Cup dicyclic or cryptodicyclic, usually with five basals and five radials. Infrabasals small and concealed or missing in most subgroups (usually five when present). Basals generally small. No anal plate, no compound radials and normally no plates separating radials and basals in the postlarval skeleton.

Arms uniserial; generally divide at primibrachs 2 and commonly further divided; generally free, though proximal brachials may be movably connected by interbrachial plates. Tegmen always flexible with calcareous spicules or grains or an irregular pattern of thin plates. Larger oral plates may be present. Mouth and ambulacral grooves always open to exterior. Pinnules always present.

Column (when present) circular, elliptical or five-sided in cross section, with or without cirri on nodals. Attachment by distal cirri, radix or terminal disc. Column may be missing or transformed, e.g. into cirriferous centrodorsal in Comatulida.

Comments: The Articulata were the only group of crinoids to survive later than the Triassic, and include all living forms. Some members of the sessile orders Isocrinida, Millericrinida, Cyrtocrinida and Bourgueticrinida have survived to the present, but it is the free-living Comatulida (the feather stars) that include the vast majority of modern taxa. Though generally treated as a separate subclass of the Crinoidea, Articulata are actually a derived subgroup of the Cladida, specifically of the Dendrocrinida. While Weinberg Rasmussen (1978) included only Mesozoic and Caenozoic forms in the Articulata, Webster et al. (2003) included the Carboniferous-Permian Ampelocrinida as basal articulates.

Compared to earlier crinoids, Articulata are marked by a reduction in the plating of the cup, most significantly the increased flexibility of the tegmen and the exposure of the mouth and ambulacral grooves, though this was paralleled by other evolutionary lines in the Dendrocrinida and Flexibilia. The loss of the column and the adoption of a free-living mode of life has occurred in more than one articulate lineage - Jaekel (1918) grouped these forms together as the Libera, but Ubaghs et al. (1978) regarded this as a polyphyletic grouping. The Uintacrinida and Roveacrinida completely lost the stem as well as significantly lightening the skeleton and adopted a planktonic mode of life.

Phylogeny

<==Articulata [Astylida, Canaliculata, Libera, Liberidae, Neocrinoidea, Pinnata, Stomatocrinoidea]
   |  i. s.: Dolichocrinus de Loriol 1891 [=Tetanocrinus Jaekel 1891]
   |           `--*D. aberrans (de Loriol 1882) [=Eugeniacrinus aberrans, *Tetanocrinus aberrans]
   |         Acariaeocrinus Biese 1935 [=Microcrinus Terquem & Piette 1865 non Emmons 1858]
   |           `--*A. liasinus (Terquem & Piette 1865) [=*Microcrinus liasinus]
   |--Roveacrinida
   |    |--Roveacrinidae
   |    `--Saccocomidae
   |--Uintacrinida [Innatantes, Uintacrinacea]
   |    |--Uintacrinus Grinnell 1876 [Uintacrinidae]
   |    |    `--*U. socialis Grinnell 1876 [incl. U. westfalicus Schlüter 1878]
   |    `--Marsupites d’Orbigny 1852 (see below for synonymy)
   |         `--M. testudinarius (von Schlotheim 1820) (see below for synonymy)
   |--Millericrinida [Apiocrinacea]
   |    |--Millericrinina
   |    `--+--Hyocrinidae
   |       `--Cyrtocrinida [Coadunata, Compacta]
   |            |--Cyrtocrinina
   |            `--Holopodina
   |--Ampelocrinida
   |    |--Ampelocrinidae
   |    `--Corythocrinidae
   |         |--Campbellicrinus
   |         |--Araeocrinus Strimple & Watkins 1969
   |         |    `--*A. bassus Strimple & Watkins 1969
   |         |--Hutkocrinus Webster, Maples et al. 2003
   |         |    `--*H. kermanensis Webster, Maples et al. 2003
   |         |--Corythocrinus Kirk 1946
   |         |    |--*C. insculptus Kirk 1946
   |         |    `--C. fragilis
   |         `--Logocrinus Goldring 1923
   |              |--*L. geniculatus Goldring 1923
   |              |--L. brandoni Sigler, White & Kesling 1971
   |              `--L. delicatulus (Lane, Waters & Maples 2003) [=Bridgerocrinus delicatulus]
   |--Isocrinida [Isocrinina, Pentacrinacea]
   |    |  i. s.: Proisocrinus Clark 1910 [Proisocrinidae]
   |    |           `--*P. ruberrimus Clark 1910
   |    |--Isocrinidae
   |    |--Holocrinidae
   |    |    |--Moenocrinus Hildebrand 1926
   |    |    |    `--*M. deeckei Hildebrand 1926
   |    |    `--Holocrinus Wachsmuth & Springer 1886
   |    |         |--*H. beyrichi (Picard 1883) [=Encrinus beyrichi]
   |    |         `--H. wagneri (Benecke 1887)
   |    `--+--Comatulida
   |       `--Pentacrinitidae [Pentacrinidae, Pentacrininae]
   |            |--Seirocrinus Gislén 1924
   |            |    `--S. fasciculosus (von Schlotheim 1813) (see below for synonymy)
   |            `--Pentacrinites Blumenbach 1804 (see below for synonymy)
   |                 |--*P. fossilis Blumenbach 1804 (see below for synonymy)
   |                 |--P. collenoti
   |                 |--P. dargniesi
   |                 |--‘Pentacrinus’ laevigatus
   |                 |--P. sorlinensis
   |                 `--P. versistellatus
   `--Bourgueticrinida [Bourgueticrinina]
        |--Bathycrinidae
        |--Phrynocrinidae
        |    |--Phrynocrinus Clark 1907
        |    |    `--*P. nudus Clark 1907
        |    `--Zeuctocrinus Clark 1973
        |         `--*Z. gisleni Clark 1973
        |--Porphyrocrinidae
        |    |--Porphyrocrinus Gislén 1925
        |    |    `--*P. verrucosus Gislén 1925
        |    `--Naumachocrinus Clark 1912
        |         `--*N. hawaiiensis Clark 1912
        `--Bourgueticrinus d’Orbigny 1841 (see below for synonymy)
             |--*B. ellipticus (Miller 1821) [=Apiocrinites ellipticus]
             |--B. cylindricus
             |--B. danicus
             |--B. hagenowii
             |--B. hureae
             |--*Metapiocrinus’ minutus Jaekel 1918
             |--B. papilliformis
             `--*Mesocrinus’ suedicus Carpenter 1881

Bourgueticrinus d’Orbigny 1841 [incl. Mesocrinus Carpenter 1881, Metapiocrinus Jaekel 1918, Volvola Lhwyd ex Valette 1917; Bourgueticrinidae]

Marsupites d’Orbigny 1852 [=Marsupiocrinites de Blainville 1830; incl. Sitularia Cumberland 1826; Marsupitidae]

Marsupites testudinarius (von Schlotheim 1820) [=Encrinites testudinarius; incl. M. americanus Springer 1911, M. laevigatus Forbes in Dixon 1850, M. lamberti Besairie 1936, M. milleri Mantell 1822, *M. ornatus Miller 1821, *Sitularia trianguliformis Cumberland 1826]

Pentacrinites Blumenbach 1804 [=Pentacrinite (l. c.), Pentacrinus Miller 1821, Pentracinus (l. c.); incl. Extracrinus Austin & Austin 1847, Heterocrinus Fraas 1858 non Hall 1847]

*Pentacrinites fossilis Blumenbach 1804 [=*Pentacrinus fossilis; incl. Pentacrinites briareus Miller 1821, *Extracrinus briareus, Pentacrinites britannicus von Schlotheim 1813]

Seirocrinus fasciculosus (von Schlotheim 1813) [=Pentacrinites fasciculosus; incl. Pentacrinites briaroides Quenstedt 1852, Pentacrinites colligatus Quenstedt 1852, Pentacrinus hiemeri Koenig 1825, Extracrinus lepidotus Austin & Austin 1847, Pentacrinites subangularis Miller 1821, *Seirocrinus subangularis]

* Type species of generic name indicated

References

McIntosh, G. C. 2001. Devonian cladid crinoids: Families Glossocrinidae Goldring, 1923, and Rutkowskicrinidae new family. Journal of Paleontology 75 (4): 783-807.

Moore, R. C., N. G. Lane, H. L. Strimple, J. Sprinkle & R. O. Fay. 1978. Inadunata. In Treatise on Invertebrate Paleontology pt. T. Echinodermata 2. Crinoidea (R. C. Moore & C. Teichert, eds.) vol. 2 pp. T520-T759. The Geological Society of America, Inc.: Boulder (Colorado), and The University of Kansas: Lawrence (Kansas).

Ubaghs, G. 1978. Skeletal morphology of fossil crinoids. In Treatise on Invertebrate Paleontology pt. T. Echinodermata 2. Crinoidea (R. C. Moore & C. Teichert, eds.) vol. 1 pp. T58-T216. The Geological Society of America, Inc.: Boulder (Colorado), and The University of Kansas: Lawrence (Kansas).

Ubaghs, G., N. G. Lane, H. Weinberg Rasmussen & H. L. Strimple. 1978. Evolution. In Treatise on Invertebrate Paleontology pt. T. Echinodermata 2. Crinoidea (R. C. Moore & C. Teichert, eds.) vol. 2 pp. T275-T316. The Geological Society of America, Inc.: Boulder (Colorado), and The University of Kansas: Lawrence (Kansas).

Webster, G. D., C. G. Maples, R. Mawson & M. Dastanpour. 2003. A cladid-dominated Early Mississippian crinoid and conodont fauna from Kerman Province, Iran and revision of the glossocrinids and rhenocrinids. Journal of Paleontology 77 (Suppl 3): 1-35.

Weinberg Rasmussen, H. 1978. Articulata. In Treatise on Invertebrate Paleontology pt. T. Echinodermata 2. Crinoidea (R. C. Moore & C. Teichert, eds.) vol. 3 pp. T813-T927. The Geological Society of America, Inc.: Boulder (Colorado), and The University of Kansas: Lawrence (Kansas).

Credits

introduction CKT080305; phylogeny CKT080216

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