Disparida
| Disparida Temporal range:
| |
|---|---|
| File:Synbathocrinus fossil crinoid (Burlington Limestone, Mississippian; Missouri, USA) 1 (17383990962).jpg | |
| Synbathocrinus from the Mississippian of Missouri, USA | |
Scientific classification 
| |
| Kingdom: | Animalia |
| Phylum: | Echinodermata |
| Class: | Crinoidea |
| Infraclass: | Inadunata |
| Parvclass: | †Disparida Moore & Laudon, 1943 |
| Orders[1] | |
_1_(17383990962).jpg){kind=link}
Disparida is an parvclass of extinct marine animals in the class Crinoidea.[2][3][1] Disparids are a speciose and morphologically diverse group of crinoids distinguished by their monocyclic calyx and slender arms without pinnules. They range from the Early Ordovician (Tremadocian) to Middle Permian, reaching their highest diversity during the Late Ordovician.[4]
While many disparids had a generalized shape typical of other stalked crinoids, some subgroups achieved strange forms. The long-lasting Calceocrinidae were recumbent forms, with a flattened crown bent back onto a stalk which rested on the seafloor. Other unusual disparid families include the armless Zophocrinidae, the spiral-armed Myelodactylidae, and the diminutive, simplified Pisocrinidae. Disparids have long been classified by the structure of their radial plates and different planes of symmetry, but a cumulative phylogenetic approach has failed to confirm the validity of many proposed subgroups. Nevertheless, Disparida itself is well-supported as a distinct monophyletic group.[4]
Major traits of Disparida include:[1][5]
- Small monocyclic calyx, without interbasal plates. Radial plates are proportionally large and may be compound (with multiple components), while basal plates are often reduced.
- Proximal branchial plates tend to fuse with their respective radials.
- Thin, uniserial arms without pinnules. Branching is typically frequent.
- Redevelopment of prominent bilateral symmetry via an axis aligned to one of the five rays making up the crown. This axis of symmetry may lie along the E ray (homocrinoid symmetry), D ray (heterocrinoid symmetry), C ray (isocrinoid symmetry), or A ray (crinoid/belemnocrinoid symmetry, which is developed to a lesser degree in other crinoids).
- Posterior plates lie above the C radial.
List of families and genera
[edit | edit source]Disparida classification is undergoing revision. Many proposed families are paraphyletic or polyphyletic.[5][6][4]
Family Acolocrinidae
Family Allagecrinidae
Family Alphacrinidae
Family Anamesocrinidae
Family Anomalocrinidae
Family Aptocrinidae
Family Athenacrinidae
Family Belemnocrinidae
Family Calceocrinidae
- Anulocrinus
- Calceocrinus
- Catatonocrinus
- Charactocrinus
- Chirocrinus
- Chiropinna
- Corvucrinus
- Cremacrinus
- Cunctocrinus
- Darraghcrinus
- Deltacrinus
- Diaphorocrinus
- Dolerocrinus
- Eohalysiocrinus
- Epihalysiocrinus
- Espanocrinus
- Grypocrinus
- Halysiocrinus
- Minicrinus
- Paracremacrinus
- Senariocrinus
- Stibarocrinus
- Synchirocrinus
- Trypherocrinus
Family Catillocrinidae
Family Cincinnaticrinidae (i.e. Heterocrinidae, paraphyletic / polyphyletic)
Family Columbicrinidae
Family Dulkumocrinidae
Family Eustenocrinidae
Family Haplocrinitidae
Family Homocrinidae (paraphyletic / polyphyletic)
Family Iocrinidae (paraphyletic)
Family Maennilicrinidae
Family Myelodactylidae
Family Pisocrinidae
Family Pygmaeocrinidae (polyphyletic)
Family Synbathocrinidae
Family Tetragonocrinidae
Family Zophocrinidae
- Agostocrinus?
- Aureocrinus
- Brutopisocrinus
- Calcycanthocrinus
- Changinocrinus
- Claviculacrinus
- Desmacriocrinus
- Gongrocrinus
- Heracrinus
- Holynocrinus
- Hypsocrinus
- Jaekelicrinus
- Junocrinus
- Macnamaratylus
- Paradoxocrinus
- Perissocrinus
- Perittocrinus?
- Quiniocrinus
- Regnellicrinus
- Resetocrinus
- Stereobrachicrinus
- Tetracionocrinus?
- Thaminocrinus
- Trophocrinus
- Xisoallegocrinus
References
[edit | edit source]
- ^ a b c Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ W. I. Ausich, D. F. Wright, S. R. Cole and J. M. Koniecki. 2018. Disparid and hybocrinid crinoids (Echinodermata) from the Upper Ordovician (lower Katian) Brechin Lagerstätte of Ontario. Journal of Paleontology 92(5):850-871 [S. Cole/S. Cole]
- ^ Y. Y. Mao, G. D. Webster, W. I. Ausich, Y. Li, Q. L. Wang and M. Reich. 2018. A new crinoid fauna from the Taiyuan Formation (early Permian) of Henan, North China. Journal of Paleontology 92:1066-1080
- ^ a b c Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ a b Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
Lua error in Module:Taxonbar at line 165: attempt to index field 'wikibase' (a nil value).
