Tropiometracea

Fossil of Pterocoma pennata in the Paläontologische Museum München, copyright Ghedoghedo.

Belongs within: Comatulidia.
Contains: Charitometridae, Notocrinacea, Conometridae, Thalassometridae.

The Tropiometracea are a group of feather stars in which the pinnules are prismatic in shape with a triangular cross-section (Wienberg Rasmussen 1978).

Characters (from Wienberg Rasmussen 1978): Centrodorsal hemispherical or conical to truncated conical, columnar or discoidal. Adult specimens often with flattened, cirrus-free dorsal area, which may be rugose or tuberculate. With or without a radial dorsal star, radial pits and subradial cleft. Cirrus sockets large, without distinct ornament or with articular tubercles, occasionally with marginal crenellae. Sockets arranged in (five or) 10 distinct columns or irregular and crowded, tending to form 10, 15 or 20 lateral columns. Cirrals with or without dorsal spine. Centrodorsal cavity narrow to moderate, generally less than three-tenths of centrodorsal diameter except for very small specimens. Rod-shaped basals present, generally exposed in interradial points. Surface of radials variable, often low or concealed, but may be moderate to large and recumbent or overhanging. Articular face of radials gently sloping to steep, almost vertical and often high. Ventral muscular fossae low and wide to high and wide or narrow. Radial cavity narrow to wide. Arms divided at primibranchs 2 and commonly at some or all secundibranchs 2 and tertibrachs 2, seldom quartibrachs 2, occasionally secundibrachs 4 and tertibrachs 4. Synarthry at brachials 1–2 may be flat or embayed, often narrow. Syzygy at brachials 3–4, seldom at brachials 1–2 or distal branches. Further syzygy with variable intervals through distal branches. Pinnulation complete; pinnules distinctly prismatic, triangular in section with dorsal keel (unknown in most fossil species). Distal pinnules extend beyond tip of arm. Ambulacral covering plates often distinct along pinnules. Mouth central.

Tropiometracea [Tropiometrida, Thalassometrida, Thalassometrina, Thalassometroida]
    |--+--NotocrinaceaUL78
    |  `--AsterometridaeUL78
    |       |--Asterometra Clark 1907WR78
    |       |    |--*A. macropoda (Clark 1907) [=Antedon macropoda]WR78
    |       |    `--A. anthus (Clark 1907)MG-H11
    |       `--Pterometra Clark 1909WR78
    |            |--*P. trichopoda (Clark 1908) [=Ptilometra trichopoda]WR78
    |            `--P. pulcherrimaWR78
    `--+--+--ConometridaeUL78
       |  `--ThalassometridaeUL78
       `--PterocomidaeUL78
            |--Pterocoma Agassiz 1836 [=Comathulites von Schlotheim 1823, Comaturella Münster 1839]WR78
            |    |--*P. pennata (von Schlotheim 1813)WR78 (see below for synonymy)
            |    `--*Comaturella’ wagneri Münster 1839WR78
            `--Placometra Gislén 1924WR78
                 |--*P. mortenseni Gislén 1924WR78
                 `--P. laticirra (Carpenter 1880)SG93
Tropiometracea incertae sedis:
  Tropiometra Clark 1907 [Tropiometridae]WR78
    `--*T. carinata (Leach 1815) (see below for synonymy)WR78
  Ptilometra Clark 1907 [Ptilometridae]WR78
    `--*P. macronema (Müller 1846) [=Comatula macronema, Alecto macronema]WR78
  CalometridaeWR78
    |  i. s.: ‘Antedon’ discoideaC50
    |--Calometra Clark 1907WR78
    |    `--*C. callista (Clark 1907) [=Antedon callista]WR78
    |--Gephyrometra Clark 1912WR78
    |    `--*G. versicolor (Clark 1907) [=Antedon versicolor]WR78
    |--Pectinometra Clark 1912 [=Pectiometra (l. c.)]WR78
    |    `--*P. flavopurpurea (Clark 1907) [=Antedon flavopurpurea]WR78
    |--Reometra Clark 1934 [=Oreometra Clark 1912 non Aurivillius 1910]WR78
    |    `--*R. mariae (Clark 1912) [=*Oreometra mariae]WR78
    `--Neometra Clark 1912WR78
         |--*N. multicolor (Clark 1907) [=Antedon multicolor]WR78
         |--N. conaminis Clark 1914MG-H11
         |--N. gorgonia Clark 1915MG-H11
         `--N. spinosissimaU78
  CharitometridaeC50
  PseudoconometridaeE01
    |--Pseudoconometra Eagle 2001E01
    |    `--*P. coromandelensis Eagle 2001E01
    `--Moanametra Eagle 2001E01
         `--*M. torehinaensis Eagle 2001E01

*Pterocoma pennata (von Schlotheim 1813)WR78 [=Asteriatites pennatusWR78, Antedon pennataB89, *Comathulites mediterraneaeformis von Schlotheim 1823WR78, Geocoma pennataWR78, Ophiurites pennatus von Schlotheim 1820WR78; incl. Comatula pinnata Goldfuss 1831WR78, *Pterocoma pinnataWR78]

*Tropiometra carinata (Leach 1815) [=Alecto carinata, Antedon carinata, Comatula carinata Lamarck 1816; incl. T. picta]WR78

*Type species of generic name indicated

References

[B89] Boehm, G. 1889. Ein Beitrag zur Kenntniss fossiler Ophiuren. Berichte der Naturforschenden Gesellschaft zu Freiburg I. B. 4: 232–287, pls 4–5.

[C50] Clark, A. H. 1950. A monograph of the existing crinoids. Vol. 1. The comatulids. Part 4c. Superfamily Tropiometrida (the families Thalassometridae and Charitometridae). Bulletin of the United States National Museum 82 vol. 1 (4c): 1–383.

[E01] Eagle, M. K. 2001. New fossil crinoids (Articulata: Comatulida) from the late Oligocene of Waitete Bay, northern Coromandel Peninsula, New Zealand. Records of the Auckland Museum 37: 81–92.

[MG-H11] McEnnulty, F. R., K. L. Gowlett-Holmes, A. Williams, F. Althaus, J. Fromont, G. C. B. Poore, T. D. O’Hara, L. Marsh, P. Kott, S. Slack-Smith, P. Alderslade & M. V. Kitahara. 2011. The deepwater megabenthic invertebrates on the western continental margin of Australia (100–1100 m depths): composition, distribution and novelty. Records of the Western Australian Museum Supplement 80: 1–191.

[SG93] Simms, M. J., A. S. Gale, P. Gilliland, E. P. F. Rose & G. D. Sevastopulo. 1993. Echinodermata. In: Benton, M. J. (ed.) The Fossil Record 2 pp. 491–528. Chapman & Hall: London.

[U78] Ubaghs, G. 1978. Skeletal morphology of fossil crinoids. In: Moore, R. C., & C. Teichert (eds) Treatise on Invertebrate Paleontology pt T. Echinodermata 2. Crinoidea vol. 1 pp. T58–T216. The Geological Society of America, Inc.: Boulder (Colorado), and The University of Kansas: Lawrence (Kansas).

[UL78] Ubaghs, G., N. G. Lane, H. Wienberg Rasmussen & H. L. Strimple. 1978. Evolution. In: Moore, R. C., & C. Teichert (eds) Treatise on Invertebrate Paleontology pt T. Echinodermata 2. Crinoidea vol. 2 pp. T275–T316. The Geological Society of America, Inc.: Boulder (Colorado), and The University of Kansas: Lawrence (Kansas).

[WR78] Wienberg Rasmussen, H. 1978. Articulata. In: Moore, R. C., & C. Teichert (eds) Treatise on Invertebrate Paleontology pt T. Echinodermata 2. Crinoidea vol. 3 pp. T813–T927. The Geological Society of America, Inc.: Boulder (Colorado), and The University of Kansas: Lawrence (Kansas).

Leave a comment

Your email address will not be published. Required fields are marked *