Lepidocystidae
| Lepidocystidae Temporal range:
| |
|---|---|
| The lepidocystid Kinzercystis | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Echinodermata |
| Class: | †Eocrinoidea |
| Order: | †Imbricata |
| Family: | †Lepidocystidae Durham 1967 |
| Genera | |
| |
The Lepidocystidae (sometimes misspelled Lepidocystoidae, not to be confused with the class Lepidocystoidea that was proposed at the same time but later abandoned) are an extinct family that constitue the most basal known group within the paraphyletic class "Eocrinoidea", and therefore within the subphylum Blastozoa as a whole.[1] Its members, along with the transitional Felbabkacystidae, are also known as "imbricates" or "imbricate Eocrinoids" after the likewise paraphyletic order Imbricata.[2]
Lepidocystids demonstrate that echinoderms had already developed five equally well-developed ambulacra in five-sided radial symmetry. However, this group had not yet developed pentameral symmetry in its plate arrangements.[3]
Phylogeny
The following cladogram, after Nardin et al. 2017 with slight modifications,[4] shows the basal position of the Lepidocystidae and the transitional position of the Felbabkacystidae:
| Blastozoa |
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Taxonomy
The following genera and species are members of the Lepidocystidae:[1][5]
- Family Lepidocystidae (Durham 1967)
- Lepidocystis (Foerste 1938)
- L. wanneri (Foerste 1938)
- Kinzercystis (Sprinkle 1973)
- K. durhami (Sprinkle 1973)
- Vyscystis (Fatka & Kordule 1990)
- V. ubaghsi (Fatka & Kordule 1990)
- V.? spinosa (Wang et al. 2024)
- Lepidocystis (Foerste 1938)
A an additional lepidocystid species similar to Lepidocystis has been found in Cambrian Stage 3 rocks from western Gondwana, but not yet formally described. If confirmed as a lepidocystoid, it would extend the range of the clade to the earliest stage known to contain confirmed echinoderms.[6]
References
- ^ a b Wang et al. 2024, p. 3
- ^ Mooi et al. 2024, p. 480
- ^ Sprinkle 1973, pp. 41–42
- ^ Nardin et al. 2017, p. 680 (Note: This source misspells "Lichenoididae" as "Lichenoidae" and "Lepidocystidae" as "Lepidocystoidae", contrary to the Treatise on Invertebrate Paleontology, Part S, Echinodermata 1, and other sources such as the PBDB and the IRMNG; this cladogram shows the more common spellings and placements.)
- ^ Sprinkle 1973, pp. 61–75
- ^ Smith, Zamora & Javier Álvaro 2013, pp. 3–4
Works cited
- Mooi, Rich; Lefebvre, Bertrand; Guensburg, Thomas E.; Nohejlová, Martina; Dupichaud, Christophe (December 2024). "Approaches to understanding echinoderm origins. Part 2: Questioning conceptual models". Cahiers de Biologie Marine. 65: 463–490. doi:10.21411/CBM.A.604F2876.
- Nardin, Elise; Lefebvre, Bertrand; Fatka, Oldřich; Nohejlová, Martina; Kašička, Libor; Šinágl, Miroslav; Szabad, Michal (2017). "Evolutionary implications of a new transitional blastozoan echinoderm from the middle Cambrian of the Czech Republic". Journal of Paleontology. 91 (4): 672–684. Bibcode:2017JPal...91..672N. doi:10.1017/jpa.2016.157.
- Smith, A. B.; Zamora, Samuel; Javier Álvaro, J. (2013). "The oldest echinoderm faunas from Gondwana show that echinoderm body plan diversification was rapid". Nature Communications 2391. doi:10.1038/ncomms2391.
- Sprinkle, James (1973). "Morphology and evolution of blastozoan echinoderms". Special Publication of the Museum of Comparative Zoology, Harvard University. Retrieved 29 October 2024.
- Wang, DeZhi; Nohejlová, Martina; Sun, ZheXin; Zeng, Han; Lefebvre, Bertrand; Yang, XingLian; Zhao, FangChen (2024). "First report of lepidocystid echinoderm in the Cambrian of North China: Evolutionary and Palaeobiogeographic implications". Palaeogeography, Palaeoclimatology, Palaeoecology. 644 112194. doi:10.1016/j.palaeo.2024.112194.