Sidneyia – Wikipedia

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Extinct genus of arthropods

Sidneyia is an extinct arthropod known from fossils found from the Early to the Mid Cambrian of China and the Burgess Shale formation of British Columbia. 144 specimens of Sidneyia are known from the Greater Phyllopod bed, where they comprise 0.27% of the community.[1]

General description[edit]

Sidneyia ranged from 2 to 5 inches (51 to 127 mm) in length and is one of the largest arthropods found at the site. It is thought to have been a benthic carnivore and scavenger that walked along the sea floor in search of hard-shelled prey. Gut contents have revealed that Sidneyia fed largely on small trilobites, as well as on brachiopods, hyoliths and small arthropods. The gut was narrow, but widens posteriorly to form a pocket where digestion presumably took place. The retention of feces likely indicates infrequent feeding[2] Its exquisitely preserved gnathobases resemble those of Limulus, and were probably used to crush prey.[3]

Sidneyia was discovered in 1910 during the first day of Charles Walcott’s exploration of the Burgess Shale. He named it after his elder son, Sidney, who had helped to locate the site and collect the specimen. The species name, Sidneyia inexpectans, is derived from the meaning of “Sidney’s surprise”.

About 200 specimens have been documented.

Sidneyia sinica was named in 2002 from a specimen found in the Maotianshan Shales.[4] However, it has since been rejected from the genus, and other indeterminate specimens assigned to the genus from the Spence Shale and Sirius Passet lack key diagnostic characters. Specimens that can confidently assigned to the genus include Sidneyia cf. inexpectans, known from the Wuliuan Mantou Formation of North China.,[5] as well as Sidneyia minor from the Early Cambrian (Cambrian Stage 3) Xiaoshiba Biota of Yunnan, China.[6]

Taxonomy[edit]

Sidneyia has been placed as part of the Artiopoda, a group of extinct arthropods containing trilobites and their relatives,[7] more specifically as a basal member of Vicissicaudata.[6]

References[edit]

  1. ^ 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.
  2. ^ Zacaï, Axelle; Vannier, Jean; Lerosey-Aubril, Rudy (March 2016). “Reconstructing the diet of a 505-million-year-old arthropod: Sidneyia inexpectans from the Burgess Shale fauna” (PDF). Arthropod Structure & Development. 45 (2): 200–220. doi:10.1016/j.asd.2015.09.003. PMID 26410799. S2CID 12638165.
  3. ^ Bicknell, Russell D.C; Paterson, John R; Caron, Jean-Bernard; Skovsted, Christian B (2017). “The gnathobasic spine microstructure of recent and Silurian chelicerates and the Cambrian artiopodan Sidneyia : Functional and evolutionary implications”. Arthropod Structure & Development. 47 (1): 12–24. doi:10.1016/j.asd.2017.12.001. PMID 29221679. S2CID 46830374.
  4. ^ Zhang, Xingliang; Han, Jian; Shu, Degan (27 Nov 2008). “New occurrence of the Burgess Shale arthropod Sidneyia in the Early Cambrian Chengjiang Lagerstätte (South China), and revision of the arthropod Urokodia”. Alcheringa: An Australasian Journal of Palaeontology. 26: 1–8. doi:10.1080/03115510208619239. S2CID 129442308.
  5. ^ Sun, Zhixin; Zeng, Han; Zhao, Fangchen (March 2020). “First occurrence of the Cambrian arthropod Sidneyia Walcott, 1911 outside of Laurentia”. Geological Magazine. 157 (3): 405–410. doi:10.1017/S0016756819000864. ISSN 0016-7568. S2CID 202899205.
  6. ^ a b Du, Kunsheng; Bruton, David L.; Yang, Jie; Zhang, Xiguang (2023-02-13). “An early Cambrian Sidneyia (Arthropoda) resolves the century-long debate of its head organization”. Science China Earth Sciences. doi:10.1007/s11430-022-1019-8. ISSN 1869-1897. S2CID 257177978.
  7. ^ Stein, Martin (2013-11-01). “Cephalic and appendage morphology of the Cambrian arthropod Sidneyia inexpectans Walcott, 1911”. Zoologischer Anzeiger – A Journal of Comparative Zoology. 253 (2): 164–178. doi:10.1016/j.jcz.2013.05.001. ISSN 0044-5231.

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