{{Short description|Extinct genus of arthropods}} {{Automatic taxobox | taxon = Fieldia (worm) | fossil_range = {{Fossil range|Middle Cambrian}} | authority = Walcott, 1912 | subdivision_ranks = Species | subdivision = * ''Fieldia lanceolata'' <small>Walcott, 1912</small> }}
'''''Fieldia''''' (named after American businessman and financier Cyrus W. Field) <ref>{{cite web|url=https://burgess-shale.rom.on.ca/fossils/fieldia-lanceolata/|title=''Fieldia lanceolata''|website=Burgess Shale Fossil Gallery. Virtual Museum of Canada|date=2011}}</ref> is a genus of worms known from the Cambrian Burgess Shale, and assigned to the priapulids.<ref name=SCM1979>{{Cite journal| last1 = Conway Morris | first1 = S.| title = The Burgess Shale (Middle Cambrian) Fauna| journal = Annual Review of Ecology and Systematics| volume = 10| pages = 327–349| year = 1979| issue = 1| doi = 10.1146/annurev.es.10.110179.001551| bibcode = 1979AnRES..10..327M}}</ref>
It was originally interpreted as an arthropod; its trunk bears a dense covering of spines, and its proboscis is small.<ref name="SCM1979" /> It fed on sea-floor mud, evidenced by the frequent presence of sediments preserved in its gut.<ref name="SCM1979" /> It reached 5 cm in length.
Along with the other Cambrian priapulids ''Ottoia'', ''Selkirkia'', ''Louisella'', ''Ancalagon'', ''Scolecofurca'', and ''Lecythioscopa'', the organism was originally classified into a clade termed the Archaeopriapulida, a stem group to the Priapulids proper.<ref name='Por1983'>{{Cite journal| first1 = F. D.| title = Class Seticoronaria and Phylogeny of the Phylum Priapulida| journal = Zoologica Scripta| last1 = Por| volume = 12| issue = 4| pages = 267–272| year = 1983| doi = 10.1111/j.1463-6409.1983.tb00510.x | s2cid = 85091685}}</ref> However, the morphological similarity of these organisms to their modern cousins is remarkable, especially for the Burgess Shale,<ref>{{Cite journal | title = Anatomy and lifestyles of Early Cambrian priapulid worms exemplified by Corynetis and Anningvermis from the Maotianshan Shale (SW China) | year = 2004 | journal = Lethaia | pages = 21–33 | first1= D. Y. | last2 = Vannier | first2 = J. | last3 = Chen | first3 = J.Y. | doi = 10.1080/00241160410005088 | last1 = Huang | volume = 37 | issue = 1 | bibcode = 2004Letha..37...21H }}</ref> and their similarity to the modern genus ''Maccabeus'' suggests that they are in the Seticoronaria stem group, and thus are true crown-group priapulids.<ref name=Por1983/> A phylogenetic analysis does not provide a great deal of resolution to the relationships between these basal worms.<ref>{{Cite journal| first = M. A. | title = Cambrian and Recent Disparity: the Picture from Priapulids | journal = Paleobiology | volume = 24 | issue = 2| last = Wills | pages = 177–199 | date = 1 April 1998 | jstor = 2401237 | doi = 10.1666/0094-8373(1998)024[0177:CARDTP]2.3.CO;2 | s2cid = 88647544 }}</ref>
18 species of ''Fieldia'' are known from the Greater Phyllopod bed, where they comprise 0.03% of the community.<ref name=Caron2006>{{cite journal|last1=Caron |first1=Jean-Bernard|last2=Jackson |first2=Donald A.|title=Taphonomy of the Greater Phyllopod Bed community, Burgess Shale|journal=PALAIOS |volume=21 |issue=5 |pages=451–65|date=October 2006|doi=10.2110/palo.2003.P05-070R|jstor=20173022|bibcode=2006Palai..21..451C |s2cid=53646959 }}</ref>
==References== {{Reflist}}
==External links== * {{cite web|url=https://burgess-shale.rom.on.ca/fossils/fieldia-lanceolata/|title=''Fieldia lanceolata''|website=Burgess Shale Fossil Gallery. Virtual Museum of Canada|archive-url=https://web.archive.org/web/20230326160413/https://burgess-shale.rom.on.ca/fossils/fieldia-lanceolata/|archive-date=2023-03-26|url-status=live}}
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Category:Burgess Shale fossils Category:Burgess Shale animals Category:Prehistoric protostome genera Category:Cambrian genus extinctions