| Revision as of 03:48, 9 August 2023 editInedibleHulk (talk | contribs)Extended confirmed users127,482 editsm The abyss was showing.← Previous edit | Latest revision as of 16:58, 19 December 2024 edit undoIxat totep (talk | contribs)Extended confirmed users2,139 edits Template:Early Echinoderms graphical timeline is currently unreadable, with text on top of text (at "standard" text size) and low-contrast colors that are a major accessibility problem. I'd love to see it restored when it is usable, but unfortunately it's noise right now. | ||
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| {{Automatic taxobox | {{Automatic taxobox | ||
| | fossil_range = {{Fossil range|prefix = ~ | 516 | PS = (Cambrian Stage 3) | ref=<ref name="Zamora2013"/>}} | | fossil_range = {{Fossil range|prefix = ~ | 516 | PS = (Cambrian Stage 3) | ref=<ref name="Zamora2013"/>}} | ||
| | image = Helicoplacus.jpg | | image = Helicoplacus USNM.jpg | ||
| | image_caption = ''H. gilberti'' ] (USNM 6063), ] | |||
| | image_caption = ''Helicoplacus guthi''<ref name="Type1963">{{cite journal |last1= Durham, J.W. |first1= & Caster, K. E. |title= Helicoplacoidea: A New Class of Echinoderms |journal= Science |volume= 140 |issue= 3568 |pages= 820–822 |date= 17 May 1963 |pmid=17746435 |last2= Caster |first2= KE |doi= 10.1126/science.140.3568.820|bibcode= 1963Sci...140..820D |s2cid= 33443660 }}</ref> | |||
| | taxon = Helicoplacus | | taxon = Helicoplacus | ||
| | authority = | | authority = | ||
| | subdivision_ranks = Species | | subdivision_ranks = Species | ||
| | subdivision = | | subdivision = * ''Helicoplacus curtisi'' | ||
| * ''Helicoplacus curtisi'' | |||
| * ''Helicoplacus guthi'' | * ''Helicoplacus guthi'' | ||
| | range_map = Helicoplacus finds.svg | | range_map = Helicoplacus finds.svg | ||
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| Other contemporaneous echinoderms are known to have existed from their dissociated plates, but other than a few possible edrioasteroids, ''Helicoplacus'' is the earliest echinoderm that is well enough preserved to analyze its characteristics. One much earlier form called '']'' has been hypothesized to be an ] echinoderm because of its fivefold symmetry, though it appears to lack stereoms and a mouth. | Other contemporaneous echinoderms are known to have existed from their dissociated plates, but other than a few possible edrioasteroids, ''Helicoplacus'' is the earliest echinoderm that is well enough preserved to analyze its characteristics. One much earlier form called '']'' has been hypothesized to be an ] echinoderm because of its fivefold symmetry, though it appears to lack stereoms and a mouth. | ||
| {{Early Echinoderms graphical timeline}} | |||
| ''Helicoplacus'' is thought to have been a suspension feeder living at moderate depths in highly oxygenated water with strong enough currents to ensure a steady food supply. It is typically found in greenish ]s and, rarely found in shallow water ]s and ]s. The helically spiraling rows of plates radiating from the base, which in life probably was anchored in the muddy substrate.<ref>{{cite web| url = http://www.usna.edu/Users/oceano/pguth/website/pl00001.htm| url-status = dead| archive-url = https://web.archive.org/web/19990203180851/http://www.usna.edu/Users/oceano/pguth/website/pl00001.htm| archive-date = 1999-02-03| title = Associate Professor Peter L. Guth Home Page}} |
''Helicoplacus'' is thought to have been a suspension feeder living at moderate depths in highly oxygenated water with strong enough currents to ensure a steady food supply. It is typically found in greenish ]s and, rarely found in shallow water ]s and ]s. The helically spiraling rows of plates radiating from the base, which in life probably was anchored in the muddy substrate.<ref>{{cite web| url = http://www.usna.edu/Users/oceano/pguth/website/pl00001.htm| url-status = dead| archive-url = https://web.archive.org/web/19990203180851/http://www.usna.edu/Users/oceano/pguth/website/pl00001.htm| archive-date = 1999-02-03| title = Associate Professor Peter L. Guth Home Page}}</ref> | ||
| == Stratigraphic distribution == | == Stratigraphic distribution == | ||
| ''Helicoplacus'' is one of the earliest mineralizing echinoderms, appearing alongside close relatives ''Polyplacus'' and ''Waucobella'' in the ], among strata notable for an exceptional abundance of echinoderm fossils (including also edrioasteroid fragments).<ref name="Smith2013nc">{{Cite journal |
''Helicoplacus'' is one of the earliest mineralizing echinoderms, appearing alongside close relatives ''Polyplacus'' and ''Waucobella'' in the ], among strata notable for an exceptional abundance of echinoderm fossils (including also edrioasteroid fragments).<ref name="Smith2013nc">{{Cite journal | title = Figure 3: Stratigraphic distribution of early to middle Cambrian echinoderms. | journal = Nature Communications | date = 2013 | doi = 10.1038/ncomms2391| pmid = 23340425 | doi-access = free | last1 = Smith | first1 = A. B. | last2 = Zamora | first2 = S. | last3 = Álvaro | first3 = J. J. | volume = 4 | page = 1385 }}</ref><ref name="Zamora2013">Zamora, S. ''et al.'' (2013). Cambrian echinoderm diversity and palaeobiogeography. In: Harper, D. A. T. & Servais, T. (eds). ''Early Palaeozoic Biogeography and Palaeogeography''. Geological Society, London, Memoirs, '''38''': 157-173.</ref> | ||
| The Poleta Formation is correlated with the as-yet unratified Cambrian Stage 3 (Series 2), giving it a provisional date of ~{{Ma|516}}.<ref>{{Cite book | | The Poleta Formation is correlated with the as-yet unratified Cambrian Stage 3 (Series 2), giving it a provisional date of ~{{Ma|516}}.<ref>{{Cite book | | ||
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| author = Peng, S.C. | author2 = Babcock, L.E. | author3 = Ahlberg, P.| | author = Peng, S.C. | author2 = Babcock, L.E. | author3 = Ahlberg, P.| | ||
| year = 2020| | year = 2020| | ||
| pages = |
pages = 565–629| | ||
| publisher = Elsevier | publisher = Elsevier | ||
| | doi = 10.1016/B978-0-12-824360-2.00019-X |
| doi = 10.1016/B978-0-12-824360-2.00019-X| | ||
| s2cid = 242177216}} | |||
| </ref> | </ref> | ||
| ==See also== | ==See also== | ||
| * '']'' | * '']'' | ||
| *] | *] | ||
| *] | *] | ||
| Line 55: | Line 53: | ||
| ] | ] | ||
| ] | ] | ||
| ] | ] | ||
| ⚫ | ] | ||
| {{paleo-echinoderm-stub}} | {{paleo-echinoderm-stub}} | ||
| ⚫ | ] | ||
Latest revision as of 16:58, 19 December 2024
Extinct genus of marine invertebrates
| Helicoplacus Temporal range: ~ 516 Ma (Cambrian Stage 3) PreꞒ Ꞓ O S D C P T J K Pg N ↓ | |
|---|---|
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| H. gilberti hypotype (USNM 6063), National Museum of Natural History | |
Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Echinodermata |
| Class: | †Helicoplacoidea |
| Genus: | †Helicoplacus |
| Species | |
| |
| |
| Areas where Helicoplacus has been found | |
Helicoplacus (often misspelled Helioplacus) is the earliest well-studied fossil echinoderm. Fossil plates are known from several regions. Complete specimens were found in Lower Cambrian strata of the White Mountains of California.
The animal was a cigar-shaped creature up to 7 centimetres (2.8 in) long that stood upright on one end. Unlike more typical echinoderms such as sea stars, Helicoplacus does not have fivefold symmetry. Instead, there is a spiral food groove on the outside along which food was moved to a mouth that is thought to be on the side. The respiratory system appears to be primitive. Although the animal does not look like a typical echinoderm, the plates are composed of the characteristic calcareous plates known as stereom that are common to all echinoderms. The ambulacrum is similar to that of the Edrioasteroidea; as a result, Helicoplacus may belong to Pelmatozoa.
Other contemporaneous echinoderms are known to have existed from their dissociated plates, but other than a few possible edrioasteroids, Helicoplacus is the earliest echinoderm that is well enough preserved to analyze its characteristics. One much earlier form called Arkarua has been hypothesized to be an ancestral echinoderm because of its fivefold symmetry, though it appears to lack stereoms and a mouth.
Helicoplacus is thought to have been a suspension feeder living at moderate depths in highly oxygenated water with strong enough currents to ensure a steady food supply. It is typically found in greenish shales and, rarely found in shallow water sandstones and limestones. The helically spiraling rows of plates radiating from the base, which in life probably was anchored in the muddy substrate.
Stratigraphic distribution
Helicoplacus is one of the earliest mineralizing echinoderms, appearing alongside close relatives Polyplacus and Waucobella in the Poleta formation, among strata notable for an exceptional abundance of echinoderm fossils (including also edrioasteroid fragments).
The Poleta Formation is correlated with the as-yet unratified Cambrian Stage 3 (Series 2), giving it a provisional date of ~516 million years ago.
See also
References
- ^ Zamora, S. et al. (2013). Cambrian echinoderm diversity and palaeobiogeography. In: Harper, D. A. T. & Servais, T. (eds). Early Palaeozoic Biogeography and Palaeogeography. Geological Society, London, Memoirs, 38: 157-173.
- ^ Smith, A. B.; Zamora, S.; Álvaro, J. J. (2013). "Figure 3: Stratigraphic distribution of early to middle Cambrian echinoderms". Nature Communications. 4: 1385. doi:10.1038/ncomms2391. PMID 23340425.
- "Associate Professor Peter L. Guth Home Page". Archived from the original on 1999-02-03.
- Peng, S.C.; Babcock, L.E.; Ahlberg, P. (2020). "Chapter 19 – The Cambrian Period". Geologic Time Scale 2020. Elsevier. pp. 565–629. doi:10.1016/B978-0-12-824360-2.00019-X. S2CID 242177216.
External links
- Pictures of 'Helicoplacus' can be found at http://www.usna.edu/Users/oceano/pguth/website/pl00001.htm
| Taxon identifiers | |
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| Helicoplacus | |
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