Rhodocrinitidae

Gilbertsocrinus tuberosus, copyright Hectonichus.

Belongs within: Eucamerata.

So many arms
Published 10 September 2007

Behold the majesty of the Rhodocrinitidae! The photo below shows fossils of Rhodocrinites kirbyi and Cribanocrinus watersianus, both Rhodocrinitidae, and comes from the Smithsonian.

The Rhodocrinitidae are a family of the Camerata, a clade of crinoids restricted to the Palaeozoic. For those not in the know, crinoids (or “sea lilies”) are a class of echinoderms, the phylum including such beasties as starfish and sea urchins, and like all echinoderms they have a skeleton of calcareous plates. The majority of fossil species were permanently attached to the sea-bed by a stalk, but the majority of recent species belong to a clade that has lost the stalk as adults and is free-living (actually, even stalkless forms start their lives attached to the substrate, but before they reach maturity they break off their stalk—Breimer 1978a). Crinoids are filter-feeders, usually with large numbers of feathery arms that are used to sieve the surrounding water (the common name for the stalkless forms is “feather star”). Even the stalkless forms seemingly never move more than is strictly necessary to occupy the optimum position for filter-feeding—as commented by Breimer (1978b), “Seemingly, the stemless crinoids have only gained the vagile capacity of active movement in order to gain efficiency as sedentary animals“.

The Camerata were characterised by the development of a calyx (the cup-shaped part of the body that the arms come off) with the skeletal plates rigidly sutured together. The tegmen (the upper covering of the central body—calyx below, tegmen above, if I understand correctly) forms a vaulted ceiling that conceals the mouth and the proximal parts of the ambulacra (the tube-foot-lined grooves that run down the arms and transport food particles to the mouth). The only external opening to the tegmen is the anus, which is usually raised on a tube (doubtless to carry food particles further from the mouth). Extra plates between the bases of the arms incorporated them into the calyx (Ubaghs 1978b), though in later camerates these were reduced, freeing the arms (Ubaghs et al. 1978). The Camerata are divided into two orders, Diplobathrida (including Rhodocrinitidae) and Monobathrida, distinguished by the number of rings of plates making up the calyx.

Rhodocrinitidae were around from the Middle Ordovician to the Lower Carboniferous. They were a heterogenous group encompassing a variety of forms (Eckert & Brett 2001). The calyx was globular (Ubaghs 1978b), obconical or bowl-shaped (Eckert & Brett 2001), and the arms could be uniserial or biserial (Eckert & Brett 2001).

The largely immobile calyx and increased numbers of pinnules (side-branches of the arms) in camerates appear to be adaptations to a rheophilic lifestyle—living in high-current environments (Breimer 1978c). Also as a probable adaptation to high currents, rhodocrinitids were attached to the substrate by coiling the end of the stalk around an anchoring object. This may have allowed for a less rigid attachment, allowing a certain degree of slippage around the anchor.

The Rhodocrinitidae were the only family of Diplobathrida to survive the Devonian, along with a number of families of Monobathrida. While the Rhodocrinitidae became extinct during the Carboniferous, the Monobathrida trickled along until the end of the Permian, which sounded the final death-knell for the camerates (Ubaghs et al. 1978).

Systematics of Rhodocrinitidae
Rhodocrinitidae [Gilbertsocrinidae, Rhodocrinidae]
|--Kyreocrinus Ausich 1986EB01
|--Luxocrinus Witzke & Strimple 1981EB01
|--Xysmacrinus Ausich 1986EB01
|--Stereoaster Foerste 1919EB01
| `--*S. squamatus Foerste 1919SW66
|--Paragazacrinus Springer 1926EB01
| `--*P. rotundus Springer 1926U78b
|--Maquoketacrinus Slocum 1924EB01
| `--*M. ornatus Slocom in Slocum & Foerste 1924U78b
|--Atactocrinus Weller 1916EB01
| `--*A. wilmingtonensis Weller 1916U78b
|--Thylacocrinus Oehlert 1878U78b
| `--T. vannioti Oehlert 1878U78b
|--Cadiscocrinus Kirk 1945U78b
| `--*C. southworthi Kirk 1945U78b
|--Condylocrinus Eichwald 1860U78b
| `--*C. verrucosus Eichwald 1860U78b
|--Elpidocrinus Strimple 1963U78b
| `--*E. tholiformis Strimple 1963U78b
|--Monstrocrinus Schmidt 1942U78b
| `--*M. securifer Schmidt 1942U78b
|--Ophiocrinus Salter 1856U78b
| `--*O. stangeri Salter 1856U78b
|--Paradiabolocrinus Brower & Veinus 1974U78b
| `--*P. irregularis Brower & Veinus 1974U78b
|--Sphaerotocrinus Goldring 1923U78b
| `--*S. ornatus Goldring 1923U78b
|--Trichinocrinus Moore & Laudon 1943U78b
| `--*T. terranovicus Moore & Laudon 1943U78b
|--Lyriocrinus Hall 1852EB01
| |--*L. dactylus (Hall 1843) [=Marsupiocrinites dactylus]U78b
| `--L. melissaUL78
|--Diamenocrinus Oehlert 1891EB01
| |--*D. jouani Oehlert 1891U78b
| `--D. stellatusU78a
|--Rhipidocrinus Beyrich in Zittel 1879 [=Ripidocrinus Wachsmuth & Springer 1881]U78b
| |--*R. crenatus (Goldfuss 1831) [=Rhodocrinites crenatus, *Ripidocrinus crenatus]U78b
| `--R. perloricatusU78b
|--Acanthocrinus Roemer 1850U78b
| |--*A. longispina Roemer 1850U78b
| `--A. rexU78b
|--Cribanocrinus Kirk 1944U78b
| |--*C. wortheni (Hall 1858) [=Rhodocrinus wortheni]U78b
| `--C. urceolatusU78b
|--Diabolocrinus Wachsmuth & Springer 1897U78b
| |--*D. perplexus Wachsmuth & Springer 1897U78b
| |--D. arbucklensisA96
| `--D. vesperalisU78b
|--Rhodocrinites Miller 1821 [=Rhodocrinus Agassiz 1836]U78b
| |--*R. verus Miller 1821 [=*Rhodocrinus verus]U78b
| |--R. baccatus Wright 1939SG93
| |--R. kirkbyiU78b
| `--R. watersianusU78a
`--Gilbertsocrinus Phillips 1836 (see below for synonymy)U78b
|--*G. calcaratus Phillips 1836U78b
|--G. tuberculosusU78a
|--G. tuberosus (Lyon & Casseday 1859)U78a, U78b [=*Goniasteroidocrinus tuberosusU78b]
|--‘*Trematocrinus’ typus Hall 1860U78b
`--G. vetulusMB12

Gilbertsocrinus Phillips 1836 [incl. Goniasteroidocrinus Lyon & Casseday 1859, Goniastroidocrinus (l. c.), Ollacrinus Cumberland 1826 (n. n.), Ollacrinites de Blainville 1834, Trematocrinus Hall 1860]U78b

*Type species of generic name indicated

References

[A96] Ausich, W. I. 1996. Crinoid plate circlet homologies. Journal of Paleontology 70: 955–964.

Breimer, A. 1978a. General morphology—recent crinoids. In: Moore, R. C., & C. Teichert (eds) Treatise on Invertebrate Paleontology pt T. Echinodermata 2. Crinoidea vol. 1 pp. T9–T58. The Geological Society of America, Inc.: Boulder (Colorado), and The University of Kansas: Lawrence (Kansas).

Breimer, A. 1978b. Ecology of recent crinoids. In: Moore, R. C., & C. Teichert (eds) Treatise on Invertebrate Paleontology pt T. Echinodermata 2. Crinoidea vol. 1 pp. T316–T330. The Geological Society of America, Inc.: Boulder (Colorado), and The University of Kansas: Lawrence (Kansas).

Breimer, A. 1978c. Paleoecology—autecology. In: Moore, R. C., & C. Teichert (eds) Treatise on Invertebrate Paleontology pt T. Echinodermata 2. Crinoidea vol. 1 pp. T331–T343. The Geological Society of America, Inc.: Boulder (Colorado), and The University of Kansas: Lawrence (Kansas).

[EB01] Eckert, J. D., & C. E. Brett. 2001. Early Silurian (Llandovery) crinoids from the Lower Clinton Group, western New York State. Bulletins of American Paleontology 360: 1–88.

[MB12] Mistiaen, B., D. Brice, M. K. Zapalski & C. Loones. 2012. Brachiopods and their auloporid epibionts in the Devonian of Boulonnais (France): comparison with other associations globally. In: Talent, J. A. (ed.) Earth and Life: Global biodiversity, extinction intervals and biogeographic perturbations through time pp. 159–188. Springer.

[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.

[SW66] Spencer, W. K., & C. W. Wright. 1966. Asterozoans. In: Moore, R. C. (ed.) Treatise on Invertebrate Paleontology pt U. Echinodermata 3 vol. 1 pp. U4–U107. The Geological Society of America, Inc., and The University of Kansas Press.

[U78a] Ubaghs, G. 1978a. 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).

[U78b] Ubaghs, G. 1978b. Camerata. In: Moore, R. C., & C. Teichert (eds) Treatise on Invertebrate Paleontology pt T. Echinodermata 2. Crinoidea vol. 2 pp. T408–T519. 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).

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