Ubaghsicystis
| Ubaghsicystis Temporal range:
| |
|---|---|
| Silhouette of Ubaghsicysts | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Echinodermata |
| Class: | †Eocrinoidea |
| Genus: | †Ubaghsicystis Gil Cid & Domínguez Alonso, 2002 |
| Type species | |
| †U. segurae Gil Cid & Domínguez Alonso, 2002 | |
Ubaghsicystis is a genus of eocrinoid known from a single specimen each from the Barrios de Luna shales of Spain[1], the Burgess Shale of British Columbia,[2], and the Tarhoucht Member of the Jbel Wawrmast Formation of Morocco,[3] all from the Wuliuan (Stage 5) of the Middle Cambrian.
Etymology
The name of Ubaghsicystis honors paleontologist Georges Ubaghs for his work on Paleozoic echinoderms, particularly in Spain, where the first specimen was found.[1]
Description
Ubaghsicystis has a globular theca, or body, that is taller than it is wide, with a columnar stem. The plating of the theca forms more regular circles towards the stem, becoming more irregular towards the oral region. Epispires are present on the upper portion of the theca, but not the lower.[1] Two feeding appendages are known, with a gradual transition from the theca rather than the sort of distinct insertion seen in eocrinoids such as Gogia.[2]
While not a flattened eocrinoid itself, Ubaghsicystis is the earliest known eocrinoid to show a reduction to only two ambulacra. Its feeding appendages represent undivided BC and DE rays. The anal pyramid, typically found between the C and D rays, is on the right side of the theca.[4]
As of the time of its description in 2015, the Burgess Shale specimen of Ubaghsicystis is the earliest known Laurentian eocrinoid with a holomeric stem.[2]
References
Works cited
- Gil Cid, María Dolores; Domínguez Alonso, Patricio (December 2002). "Ubaghsicystis segurae nov. gen. y sp., nuevo Eocrinoide (Echinodermata) del Cámbrico Medio del Norte de España" [Ubaghsicystis segurae nov. gen. and sp., a new Eocrinoid (Echinoderniata) of Middle Cambrian from Northern Spain]. Coloquios de paleontología (in English and Spanish) (53). Complutense University of Madrid: 21–32. ISSN 1132-1660. Archived from the original on 20 April 2021. Retrieved 3 August 2023.
- Smith, A. B.; Zamora, Samuel; Javier Álvaro, J. (2012). "The oldest echinoderm faunas from Gondwana show that echinoderm body plan diversification was rapid". Nature Communications. 4 1385. doi:10.1038/ncomms2391.
- Sumrall, Colin D.; Zamora, Samuel (March 2015). "A columnal-bearing eocrinoid from the Cambrian Burgess Shale (British Columbia, Canada)". Journal of Paleontology. 89 (2): 366–368. Bibcode:2015JPal...89..366S. doi:10.1017/jpa.2014.54. ISSN 1937-2337. Archived from the original on 21 June 2023. Retrieved 3 August 2023.
- Zamora, Samuel; Sprinkle, James; Sumrall, Colin D. (2020). "A revaluation of rhipidocystid echinoderms based on a new flattened blastozoan from the Upper Ordovician of Maryland, USA". Acta Palaeontologica Polonica. 65 (3): 455–465. doi:10.4202/app.00718.2019.