Editing Xenusion

{{Short description|Extinct genus of panarthropods}}
{{Italic title}}
{{Speciesbox
| name =''Xenusion auerswaldae''
| fossil_range = {{Fossil range|519|521|Cambrian: Late Stage 2→Early Stage 3}}
| image =Xenusion P1060077.jpg
| image2 =Xenusion.png
| image_caption = Fossil specimen
| image2_caption = Life restoration
| genus =Xenusion
| species =auerswaldae
| parent_authority=Pompeckj, 1927
| authority =Pompeckj, 1927
| range_map =
| range_map_caption =
| synonyms_ref =
| synonyms =
}}

'''''Xenusion auerswaldae''''' is an early [[lobopodian]] known from three<ref>{{cite news |title=Oudste fossiel van Nederland naar Hunebedcentrum: 600 miljoen jaar oud |url=https://www.rtvdrenthe.nl/nieuws/15139565/oudste-fossiel-van-nederland-naar-hunebedcentrum-600-miljoen-jaar-oud |access-date=7 November 2024 |work=www.rtvdrenthe.nl |date=22 November 2022 |language=nl}}</ref> specimens found in [[glacial erratics]] on the [[Baltic Sea|Baltic]] coast of Germany.<ref name="Dzik1989">{{Cite journal | last1 = Dzik | first1 = J. | last2 = Krumbiegel | first2 = G. N. | doi = 10.1111/j.1502-3931.1989.tb01679.x | title = The oldest 'onychophoran' ''Xenusion'': A link connecting phyla? | journal = Lethaia | volume = 22 | issue = 2 | pages = 169 | year = 1989 | bibcode = 1989Letha..22..169D }}</ref> Another specimen, discovered shortly after the holotype, was briefly observed but soon went missing. Except for this lost specimen, the fossils probably originated in the Kalmarsund Sandstone of Southern [[Sweden]],<ref>{{Cite journal |last1=Jaeger |first1=Hermann |last2=Martinsson |first2=Anders |date=1967-01-31 |title=Remarks on the Problematic Fossil ''Xenusion Auerswaldae'' |url=https://doi.org/10.1080/11035896709455501 |journal=Geologiska Föreningen i Stockholm Förhandlingar |volume=88 |issue=4 |pages=435–452 |doi=10.1080/11035896709455501 |issn=0016-786X|url-access=subscription }}</ref> which was deposited in the Lower Cambrian (Upper Tommotian–Lower Atdabanian; Stages 2→3).<ref name="Han2008">{{Cite journal | last1 = Han | first1 = J. | last2 = Zhang | first2 = Z. -F. | last3 = Liu | first3 = J. -N. | title = A preliminary note on the dispersal of the Cambrian Burgess Shale-type faunas | doi = 10.1016/j.gr.2007.09.001 | journal = Gondwana Research | volume = 14 | pages = 269–276 | year = 2008 | issue = 1–2 }}</ref> It is the oldest currently known lobopodian with soft body [[fossils]].<ref>{{Cite journal |last1=Ou |first1=Qiang |last2=Mayer |first2=Georg |date=2018-09-20 |title=A Cambrian unarmoured lobopodian, †''Lenisambulatrix humboldti'' gen. et sp. nov., compared with new material of †''Diania cactiformis'' |journal=Scientific Reports |language=en |volume=8 |issue=1 |pages=13667 |doi=10.1038/s41598-018-31499-y |issn=2045-2322 |pmc=6147921 |pmid=30237414|bibcode=2018NatSR...813667O }}</ref>

The specimens are not especially well preserved. The older specimen is 10&nbsp;cm or so in length with a narrow, weakly segmented body. Assuming it was the posterior section, the specimen was estimated to be part of an animal about 20&nbsp;cm in length.<ref name="Dzik1989" /> A depression runs up the bottom on all but the rearmost segments. There is a slightly bulbous termination, and each segment before that seems to have a single pair of tapering annulated legs similar to the modern [[velvet worm|onychophoran]], but without specialized feet and claws. More than 10 body segments were present.<ref name=":0">{{Cite journal |last1=Liu |first1=Jianni |last2=Dunlop |first2=Jason A. |date=2014-03-15 |title=Cambrian lobopodians: A review of recent progress in our understanding of their morphology and evolution |url=https://www.sciencedirect.com/science/article/pii/S003101821300285X |journal=Palaeogeography, Palaeoclimatology, Palaeoecology |series=Cambrian Bioradiation |language=en |volume=398 |pages=4–15 |doi=10.1016/j.palaeo.2013.06.008 |bibcode=2014PPP...398....4L |issn=0031-0182|url-access=subscription }}</ref> There is presumably a spine on each body bump and faint transverse parallel striations on the annulations on the legs.<ref name="Dzik1989" /><ref name=":0" /> The legs of what is possibly the foremost segments are either absent or not preserved. The head is believed to be missing or poorly preserved. Based on a new specimen that shows the anterior section, it possibly had a long narrow [[proboscis]],<ref name="Dzik1989" /> but this also suggested to be a preservational artefact.<ref>RAMSKÖLD, L. and CHEN, J.-Y. 1998. Cambrian lobopodians: morphology and phylogeny. In EDGECOMBE, G. D. (ed.) Arthropod Fossils and Phylogeny, Columbia University Press, New York, 107–150 pp.</ref>

''Xenusion'' has been reinterpreted as an [[Ediacaran biota|Ediacaran]] frond animal by Tarlo, and a drawing of that interpretation has been presented by McMenamin.<ref>{{Cite journal |last=McMenamin |first=Mark A. S. |date=1986 |title=The Garden of Ediacara |url=https://doi.org/10.2307/3514512 |journal=PALAIOS |volume=1 |issue=2 |pages=178–182 |doi=10.2307/3514512 |jstor=3514512 |issn=0883-1351|url-access=subscription }}</ref> In a photograph presented in ''[[Treatise on Invertebrate Paleontology|The Treatise on Invertebrate Paleontology]]'' Volume O, the organism's appearance seems to support the original interpretation more.  Further studies of Xenusiid close the possibility of a Rangeomorphy affinity.<ref name="Dzik1989" /><ref name=":0" />

==References==
{{Reflist}}

==External links==
*[http://www.ucmp.berkeley.edu/onychoph/onychophorafr.html Onychophora: Fossil Record]

{{Lobopodia}}
{{Taxonbar|from=Q136421}}

[[Category:Xenusia]]
[[Category:Terreneuvian first appearances]]
[[Category:Cambrian Series 2 extinctions]]
[[Category:Cambrian genus extinctions]]