Editing Aysheaia

{{Short description|Extinct genus of soft-bodied animals}}
{{Speciesbox
| fossil_range = {{Fossil range|Middle Cambrian}}
| image = Aysheaia pedunculata USNM 365608.png
| image_upright = 
| image_caption = ''Aysheaia'' specimen number USNM 365608
| grandparent_authority = [[Charles Doolittle Walcott|Walcott, 1911]]
| genus = Aysheaia
| parent_authority = Walcott, 1911
| species = pedunculata
| authority = Walcott, 1911
}}

'''''Aysheaia''''' is an extinct genus of [[Soft-bodied organisms|soft-bodied]] [[lobopodia]]n, known from the Middle [[Cambrian]] [[Burgess Shale]] of British Columbia, Canada.

== Anatomy ==
{{Multiple image
| direction = vertical
| align = left
| width = 220
| image1 = Aysheaia pedunculata2021.jpg
| image2 = 20210904_Aysheaia_pedunculata_diagrammatic_reconstruction.png
| caption2 =Life and diagrammatic reconstructions of ''Aysheaia pedunculata''
}}
''Aysheaia'' has ten body segments, each of which has a pair of spiked, annulate legs. The animal is segmented, and looks somewhat like a bloated caterpillar with a few spines added on — including six finger-like projections around the mouth and two grasping limbs on the "head". Each leg has a subterminal row of about six curved claws.<ref name="Whittington1978">{{Cite journal | jstor = 2418243| last1 = Whittington| first1 = H. B.| pages = 165–197| date = 16 November 1978| title = The Lobopod animal ''Aysheaia pedunculata'' Walcott, Middle Cambrian, Burgess Shale, British Columbia | journal = [[Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences]] | volume = 284| issue = 1000| doi = 10.1098/rstb.1978.0061|bibcode = 1978RSPTB.284..165W | doi-access = }}</ref> No jaw apparatus is evident.<ref name=Robison1985/> A pair of legs marks the posterior end of the body, unlike in onychophorans where the anus projects posteriad; this may be an adaptation to the terrestrial habit.<ref name=Robison1985/><ref name=Malcolm1994>
{{cite book
| url         = https://books.google.com/books?id=w7WIlbyhLQoC&dq=Aysheaia&pg=PA103
| title       = Invasions of the Land. The Transitions of Organisms from Aquatic to Terrestrial Life
| publisher   = Columbia University Press
| date        = 1994
| access-date  = 2022-08-21
| pages        = 103–104
| author      = Malcolm S. Gordon, Everett C. Olson 
| isbn = 9780231514026
}}</ref>

==Ecology==
Some specimens of ''Aysheaia'' have been found associated with sponges, though this does not provide direct evidence of diet.<ref>{{Cite journal |last=Frood |first=Arran |date=June 2008 |title=Palaeobiology: The Cambrian smorgasbord |url=https://www.nature.com/articles/453717a |journal=Nature |language=en |volume=453 |issue=7196 |pages=717–718 |doi=10.1038/453717a |pmid=18528369 |s2cid=4399940 |issn=0028-0836}}</ref>

==Affinity==
''Aysheaia'' is a [[lobopodian]], an extinct phylum of marine animals that are similar to modern terrestrial [[Onychophora]] (velvet worms). Notable differences are the lack of jaws and antennae, possible lack of visual organs,<ref>{{cite book | title = Arthropoda phylogeny with special reference to insects | last = Bourdreaux | first = H. Bruce | year = 1979 | url = https://archive.org/details/arthropodphyloge0000boud | page = 35| publisher = Wiley | isbn = 9780471042907 }}</ref> and the terminal mouth.<ref name=Robison1985/>

==Distribution==
''Aysheaia'' is known from [[fossil]]s found in the middle [[Cambrian]] [[Burgess shale]] of [[British Columbia]].<ref name="Robison1985">{{Cite journal| jstor = 1304837| pages = 226–235| title = Affinities of Aysheaia (Onychophora), with Description of a New Cambrian Species| last1 = Robison| journal = Journal of Paleontology| volume = 59| issue = 1| publisher = Paleontological Society| year = 1985 | first1 = R. A.}}</ref> Similar taxa are known from the lower Cambrian [[Maotianshan shale]]s of [[China]]. Other than the 20 specimens from the Greater [[Phyllopod bed]], where they comprise 2% 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> only 19 specimens of ''A. pedunculata'' are known. ''A. prolata'' was described as a separate species from the similarly-aged [[Wheeler Shale]] Formation of [[Utah]] but in fact represents the frontal appendage of a ''[[Stanleycaris]]''-like [[radiodont]].<ref>{{Cite journal|first1=Stephen |last1=Pates |first2=Allison C. |last2=Daley |first3=Javier |last3=Ortega-Hernández |year=2017 |title=''Aysheaia prolata'' from the Utah Wheeler Formation (Drumian, Cambrian) is a frontal appendage of the radiodontan ''Stanleycaris'' |journal=Acta Palaeontologica Polonica |volume=62 |issue=3 |pages=619–625 |doi=10.4202/app.00361.2017 |doi-access=free }}</ref>

==History of research==
[[File:Aysheaia pedunculata.jpg|thumb|left|Fossil of A. pedunculata on display at NMNH]]

=== Description by Walcott (1911) ===
Aysheaia was described by Walcott in his 1911 work on annelid worms; Walcott imagined that a head (not observed) was present to support a polychaete affinity.<ref name=Whittington1978/> His attention was soon drawn to the organism's resemblance to velvet worms,<ref name=Whittington1978/> which was supported by other early researchers (1920s-30s) who also recognized a similarity with the [[onychophora]],<ref>* BRUES, C. T. 1923. The geographical distribution of the Onychophora. American Naturalist, 57: 210-217. 
* WALTON, L. B. 1927. The polychaete ancestry of the insects. American Naturalist, 61: 226-250.
* HUTCHINSON, G. E. 1930. Restudy of some Burgess Shale fossils. Proceedings of the United States National Museum, 78(11): 59.
* WALCOTT, C. D. 1931. Addenda to descriptions of Burgess Shale fossils. Smithsonian Miscellaneous Collections, 85(3): 1-46.</ref> although because Aysheaia does not fall within the range of living onychophora, it has also been allocated to a phylum of its own.<ref name="Tiegs1958">{{Cite journal | last1 = Tiegs | first1 = O. W. | last2 = Manton | first2 = S. M. | doi = 10.1111/j.1469-185X.1958.tb01258.x | title = The Evolution of the Arthropoda | journal = Biological Reviews | volume = 33 | issue = 3 | pages = 255 | year = 1958 | s2cid = 84284702 }}</ref> Nevertheless, an Onychophoran affinity represented the common opinion until the fossil was redescribed in the late 1970s.<ref name=Robison1985/>

=== Major redescription by Whittington, 1978===
In the 1970s, Whittington undertook a thorough redescription,<ref name="Whittington1978" /> and associated Aysheaia with the [[tardigrade]] lineage concept promoted a couple of years earlier by Delle Cave and Simonetta,<ref>DELLE CAVE, L. AND A. M. SIMONETTA. 1975. Notes on the morphology and taxonomic position of Aysheaia (Onycophora?) and of Skania (undetermined phylum). Monitore Zoologico Italiano, 9: 67-81.</ref><ref name=Malcolm1994/> and first proposed in 1958.<ref>TIEGS, O. W. AND S. M. MANTON. 1958. The evolution of the Arthropoda. Biological Reviews, 33(3): 255-333.</ref> Thus, his interpretation places Aysheaia in the stem group to Tardigrada + Onychophora, although the view at the time was that these two modern phyla represented a group within a polyphyletic Arthropoda.<ref name="Whittington1978" /> A possible link to ''[[Xenusion]]'' was also brought up, although at this time the affinities of this group were unclear, and a link to the [[rangeomorphs]] had been proposed.<ref name="Whittington1978" />

=== Response to Whittington (1980s)===
The response to Whittington's redescription can be loosely classed into three camps: one school, predominantly Bergström, downplayed the similarities to the Onychophora and focussed on the Tardigrade interpretation; whereas others (after Simonetta and Delle Cave) recognized a group of lobopods containing Onychophora, Tardigrada, and ''Aysheaia'' (with features of both).<ref name=Robison1985/><ref name=Malcolm1994/> Robison preferred to interpret Onychophora as the sister group to Arthropoda, and placed ''Aysheaia'' in the Onychophoran stem group in a taxon called Protonychophora (solely containing ''Aysheaia''). These were differentiated from Euonychophora (the crown group) by the number of lobopod legs and claws, the unusual head appendages, the absence of eyes, jaws, antennae and slime glands, the morphology of the rear of the body, and the terminal mouth.<ref name=Robison1985/>

=== Modern era ===
[[File:Aysheaia2.jpg|thumb|upright=1.5|Reconstruction of ''A. pedunculata'']]
Later work uncovered further material of ''Xenusion'' and relatives, particularly from the Chinese fossil deposits. In light of the cladistic revolution of the 1990s, ''Aysheaia'' and its relatives were recognized as early offshoots of the lineage leading to arthropods and onychophorans.

Looking from the opposite direction, Budd points out that there are no characters that exclude ''Aysheaia'' from the Arthropoda.<ref name="Budd2001">{{Cite journal | doi = 10.1078/0044-5231-00034 | last1 = Budd | first1 = G. | title = Tardigrades as 'Stem-Group Arthropods': The Evidence from the Cambrian Fauna | issn = 0044-5231 | journal = Zoologischer Anzeiger | volume = 240 | issue = 3–4 | pages = 265–279 | year = 2001| bibcode = 2001ZooAn.240..265B }}</ref> It may be premature to assign ''Aysheaia'' to the Onychophora over Arthropoda, as it lacks any distinctive features of the onychophoran crown group; rather, both Onychophora and Arthropoda may have arisen from animals resembling ''Aysheaia'' and its kin.<ref name="Budd2009">{{Cite journal | last1 = Budd | first1 = G. E. | last2 = Telford | first2 = M. J. | doi = 10.1038/nature07890 | title = The origin and evolution of arthropods | journal = Nature | volume = 457 | issue = 7231 | pages = 812–817 | year = 2009 | pmid =  19212398|bibcode = 2009Natur.457..812B | s2cid = 2567113 }}</ref> Budd sees ''Aysheaia''-like organisms as representing a paraphyletic grade from which both modern onychophoran and arthropods evolved.<ref name="Budd2001" /><ref name="Budd2001a">{{Cite journal | last1 = Budd | first1 = G. E. | title = Why are arthropods segmented? | doi = 10.1046/j.1525-142X.2001.01041.x | journal = Evolution and Development | volume = 3 | issue = 5 | pages = 332–42 | year = 2001 | pmid =  11710765| s2cid = 37935884 }}</ref> The specialised first appendage pair of ''Aysheaia'' may be the same as the frontal appendages of [[Dinocaridida]],<ref name="Liu20062">{{cite journal |author1=Jianni Liu |author2=Degan Shu |author3=Jian Han |author4=Zhifei Zhang |author5=Xingliang Zhang |year=2006 |title=A large xenusiid lobopod with complex appendages from the Lower Cambrian Chengjiang Lagerstätte |url=http://www.app.pan.pl/article/item/app51-215.html |journal=Acta Palaeontologica Polonica |volume=51 |issue=2 |pages=215–222 |accessdate=2015-03-13}}</ref> possibly placing it near this clade.<ref name="McCall2023">{{cite journal |last1=McCall |first1=Christian |date=13 December 2023 |title=A large pelagic lobopodian from the Cambrian Pioche Shale of Nevada |url=https://www.cambridge.org/core/journals/journal-of-paleontology/article/abs/large-pelagic-lobopodian-from-the-cambrian-pioche-shale-of-nevada/11B0704C49A7730AA3E8F46EB2CA1C95 |journal=Journal of Paleontology |volume=97 |issue=5 |pages=1009–1024 |bibcode=2023JPal...97.1009M |doi=10.1017/jpa.2023.63 |access-date=13 December 2023}}</ref>

===Etymology===
The genus name commemorates a mountain peak named "Ayesha" due north of the [[Wapta Glacier]]. This peak was originally named Aysha in the 1904 maps of the region, and was renamed Ayesha after the heroine of Rider Haggard's 1887 novel ''[[She: A History of Adventure|She]]''.<ref>{{cite web|work=[[British Columbia Geographical Names Information System]] |title=Ayesha Peak |url=https://apps.gov.bc.ca/pub/bcgnws/names/10369.html |access-date=2010-05-17 |url-status=live |archive-url=https://web.archive.org/web/20110706165815/http://archive.ilmb.gov.bc.ca/bcgn-bin/bcg10?name=10369 |archive-date=2011-07-06 }}</ref>

==See also ==
*[[Paleobiota of the Burgess Shale]]

==References==
{{Reflist}}

==Further reading==
* {{Cite journal | jstor = 2418243| last1 = Whittington| first1 = H. B.| pages = 165–197| date = 16 November 1978| title = The Lobopod animal ''Aysheaia pedunculata'' Walcott, Middle Cambrian, Burgess Shale, British Columbia | journal = [[Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences]] | volume = 284| issue = 1000| doi = 10.1098/rstb.1978.0061|bibcode = 1978RSPTB.284..165W | doi-access = }}
* {{Cite journal| jstor = 1304837| pages = 226–235| title = Affinities of Aysheaia (Onychophora), with Description of a New Cambrian Species| last1 = Robison| journal = Journal of Paleontology| volume = 59| issue = 1| publisher = Paleontological Society| year = 1985 | first1 = R. A.}}

==External links==
* {{Cite web|date=2011|title=''Aysheaia pedunculata''|work=Burgess Shale Fossil Gallery|publisher=Virtual Museum of Canada|url=http://burgess-shale.rom.on.ca/en/fossil-gallery/view-species.php?id=22|archive-url=https://web.archive.org/web/20201112025257/http://burgess-shale.rom.on.ca/en/fossil-gallery/view-species.php?id=22|archive-date=2020-11-12|url-status=dead|access-date=2023-01-21}}
*[https://web.archive.org/web/20080725194109/http://www.sites.si.edu/images/exhibits/Burgess%20Shale/images/pages/Aysheaia_jpg_jpg.htm Smithsonian Institution image]
*[http://www.kumip.ku.edu/cambrianlife/Utah-Lobopods.html Lobopods from the Cambrian of Utah]
{{Lobopodia}}
{{Taxonbar|from=Q139787}}

[[Category:Cambrian invertebrates]]
[[Category:Burgess Shale fossils]]
[[Category:Xenusia]]
[[Category:Cambrian genus extinctions]]
[[Category:Wheeler Shale]]
[[Category:Fossil taxa described in 1911]]