Selkirkia

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Selkirkia
Temporal range: Cambrian Stage 3–Floian
Selkirkia columbia ROM63131.jpg
Selkirkia columbia fossil from the Burgess Shale. From Smith et al. (2015) [1]
Selkirkia columbia Restoration.png
Restoration of Selkirkia columbia
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Stem group: Priapulida (?)
Class: Archaeopriapulida
Family: Selkirkiidae
Conway Morris, 1977 [2]
Genus: Selkirkia
Walcott, 1911
Species
  • S. columbia Conway Morris, 1977
  • S. elongata Luo & Hu, 1999
  • S. sinica Luo & Hu, 1999
  • S. spencei Resser, 1939
  • S. willoughbyi Conway Morris & Robison, 1986
  • S. tsering Nanglu 2024

Selkirkia is a genus of predatory, [3] tubicolous priapulid worms known from the Middle Cambrian Burgess Shale, Ogygopsis Shale, Puncoviscana Formation [4] and the Early Ordovician Fezouata Formation. [5] 142 specimens of Selkirkia are known from the Greater Phyllopod bed, where they comprise 0.27% of the community. [6] In the Burgess Shale, 20% of the tapering, organic-walled tubes are preserved with the worm inside them, whereas the other 80% are empty (or sometimes occupied by one or more small agnostid trilobites). [3] Whilst alive, the tubes were probably vertical, whereas trilobite-occupied tubes are horizontal. [3]

Contents

Morphology

Selkirkia had a body divisible into a proboscis towards the anterior of a trunk enclosed by a tube. The proboscis would have been partially invertable and was armed with several spinules and spines, decreasing size distally overall. It was controlled by at least two sets of anterior retractor muscles. Immediately behind the proboscis was the trunk, smooth for the most part but lined with papillae towards the anterior. Surrounding the trunk was the tube, which way very finely annulated (4 annulations per 0.1 millimeters).

History

Members of Cambrorhytium were originally described as Selkirkia before their identification as a separate genus. [7]

Related Research Articles

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The Burgess Shale is a fossil-bearing deposit exposed in the Canadian Rockies of British Columbia, Canada. It is famous for the exceptional preservation of the soft parts of its fossils. At 508 million years old, it is one of the earliest fossil beds containing soft-part imprints.

<span class="mw-page-title-main">Priapulida</span> Phylum of unsegmented marine worms

Priapulida, sometimes referred to as penis worms, is a phylum of unsegmented marine worms. The name of the phylum relates to the Greek god of fertility, because their general shape and their extensible spiny introvert (eversible) proboscis may resemble the shape of a human penis. They live in the mud and in comparatively shallow waters up to 90 metres (295 ft) deep. Some species show a remarkable tolerance for hydrogen sulfide, anoxia and low salinity. Halicryptus spinulosus appears to prefer brackish shallow waters. They can be quite abundant in some areas. In an Alaskan bay as many as 85 adult individuals of Priapulus caudatus per square meter has been recorded, while the density of its larvae can be as high as 58,000 per square meter.

<i>Ottoia</i> Extinct genus of priapulid worms

Ottoia is a stem-group archaeopriapulid worm known from Cambrian fossils. Although priapulid-like worms from various Cambrian deposits are often referred to Ottoia on spurious grounds, the only clear Ottoia macrofossils come from the Burgess Shale of British Columbia, which was deposited 508 million years ago. Microfossils extend the record of Ottoia throughout the Western Canada Sedimentary Basin, from the mid- to late- Cambrian. A few fossil finds are also known from China.

Fieldia is a genus of worms known from the Cambrian Burgess Shale, and assigned to the priapulids.

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<span class="mw-page-title-main">Wheeler Shale</span> Geologic formation in Utah notable for trilobite fossils

The Wheeler Shale is a Cambrian (c. 507 Ma) fossil locality world-famous for prolific agnostid and Elrathia kingii trilobite remains and represents a Konzentrat-Lagerstätte. Varied soft bodied organisms are locally preserved, a fauna and preservation style normally associated with the more famous Burgess Shale. As such, the Wheeler Shale also represents a Konservat-Lagerstätten.

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<span class="mw-page-title-main">Ancalagon minor</span> Extinct genus of priapulid worms

Ancalagon minor is an extinct priapulid worm known from the Cambrian Burgess Shale.

<span class="mw-page-title-main">Archaeopriapulida</span> Class of marine worms

Archaeopriapulida is a group of priapulid worms known from Cambrian lagerstätte. The group is closely related to, and very similar to, the modern Priapulids. It is unclear whether it is mono- or polyphyletic. Despite a remarkable morphological similarity to their modern cousins, they fall outside of the priapulid crown group, which is not unambiguously represented in the fossil record until the Carboniferous. In addition to well-preserved body fossils, remains of several archaeopriapulid taxa are known to have been preserved primarily as organic microfossils, such as isolated scalids and pharyngeal teeth. They are probably closely related or paraphyletic to the palaeoscolecids; the relationship between these basal worms is somewhat unresolved.

<span class="mw-page-title-main">Palaeoscolecid</span> Extinct class of worms

The palaeoscolecids are a group of extinct ecdysozoan worms resembling armoured priapulids. They are known from the Lower Cambrian to the lower Ludfordian ; they are mainly found as disarticulated sclerites, but are also preserved in many of the Cambrian lagerstätten. They take their name from the typifying genus Palaeoscolex. Other genera include Cricocosmia from the Lower Cambrian Chengjiang biota. Their taxonomic affinities within Ecdysozoa have been the subject of debate.

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Cambrorhytium is an enigmatic fossil genus known from the Latham Shale (California), and the Chengjiang (China) and Burgess Shale lagerstätte. 350 specimens of Cambrorhytium are known from the Greater Phyllopod bed, where they comprise 0.7% of the community.

<i>Emeraldella</i> Extinct genus of arthropods

Emeraldella is a genus of arthropod known from the Middle Cambrian of North America. The type species E. brocki was described in 1912 from the Burgess Shale. 21 specimens of Emeraldella are known from the Greater Phyllopod bed, where they comprise < 0.1% of the community. A re-study on the species was done in 2012. A second species E. brutoni is known from the Wheeler Shale, which was described in 2011. An additional specimen of E. brutoni was described in 2019, which revealed more of the anatomy. It has been placed as a basal member of the clade Vicissicaudata within Artiopoda, a group of arthropods containing trilobites and their relatives.

<i>Louisella</i> Extinct genus of worms

Louisella is a genus of worm known from the Middle Cambrian Burgess Shale. It was originally described by Charles Walcott in 1911 as a holothurian echinoderm, and represents a senior synonym of Miskoia, which was originally described as an annelid. 48 specimens of Louisella are known from the Greater Phyllopod bed, where they comprise < 0.1% of the community. It has been stated to have palaeoscolecid-like sclerites, though this is not in fact the case.

<i>Pagetia</i> Genus of trilobites

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Scolecofurca is a genus of stem-group priapulid worm dating from the Middle Cambrian period approximately 505 million years ago.

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<i>Erratus</i> Extinct genus of Cambrian arthropod

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<span class="mw-page-title-main">Paleobiota of the Burgess Shale</span> Fossil flora and fauna of the Burgess Shale

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References

  1. Smith, M. R.; Harvey, T. H. P.; Butterfield, N. J. (2015). "The macro- and microfossil record of the Cambrian priapulid Ottoia" (PDF). Palaeontology. 58 (4): 705–721. Bibcode:2015Palgy..58..705S. doi: 10.1111/pala.12168 .
  2. Conway Morris, S (1977). "Fossil priapulid worms". Special Papers in Palaeontology. 20.
  3. 1 2 3 Chatterton, B. D. E.; Collins, D. H.; Ludvigsen, R. (2003). "Cryptic behaviour in trilobites: Cambrian and Silurian examples from Canada, and other related occurrences". In Lane, P. D; Siveter, D. J; Fortey, R. A (eds.). Trilobites and Their Relatives. Special Papers in Palaeontology. Vol. 70. The Palaeontological Association. pp. 157–173. ISBN   978-0-901702-81-4.
  4. Aceñolaza, Florencio; Guillermo, Aceñolaza (2005). "La formación Puncoviscana y unidades estratigráficas vinculadas en el neoproterozoico - Cámbrico temprano del noroeste argentino" (PDF). Latin American Journal of Sedimentology and Basin Analysis (in Spanish). 12 (2): 65–87. Retrieved 7 December 2015.
  5. Nanglu, Karma; Ortega-Hernández, Javier (March 2024). "Post-Cambrian survival of the tubicolous scalidophoran Selkirkia". Biology Letters. 20 (3). doi: 10.1098/rsbl.2024.0042 . ISSN   1744-957X. PMID   38531414.
  6. Caron, Jean-Bernard; Jackson, Donald A. (October 2006). "Taphonomy of the Greater Phyllopod Bed community, Burgess Shale". PALAIOS. 21 (5): 451–65. Bibcode:2006Palai..21..451C. doi:10.2110/palo.2003.P05-070R. JSTOR   20173022. S2CID   53646959.
  7. See Cambrorhytium .