View source for Lobopodia

{{Short description|Group of extinct worm-like animals with legs}}
{{About||a type of cell projection|Pseudopod|an explanation of very similar terms|Panarthropoda|''Lobopoda'', a genus of beetles|Lobopoda}}
{{Paraphyletic group
| fossil_range = {{fossil range|Cambrian Series 2|Early Pennsylvanian|earliest=555|latest=present|ref=<ref name="Haug2012">{{Cite journal |last1=Haug |first1=J.T. |last2=Mayer |first2=G. |last3=Haug |first3=C. |last4=Briggs |first4=D.E.G. |title=A Carboniferous non-Onychophoran Lobopodian reveals long-term survival of a Cambrian morphotype |doi=10.1016/j.cub.2012.06.066 |journal=Current Biology |year=2012 |pmid=22885062 |volume=22 |issue=18 |pages=1673–1675|doi-access=free}}</ref>}} Descendant taxa [[Onychophora]], [[Tardigrada]], and [[Euarthropoda]] survive to Recent, possible Ediacaran ichnofossils <ref>{{cite journal |last1=Chen |first1=Zhe |last2=Chen |first2=Xiang |last3=Zhou |first3=Chuanming |last4=Yuan |first4=Xunlai |last5=Xiao |first5=Shuhai |title=Late Ediacaran trackways produced by bilaterian animals with paired appendages |journal=Science Advances |date=6 June 2018 |volume=4 |issue=6 |doi=10.1126/sciadv.aao6691 |url=https://www.science.org/doi/10.1126/sciadv.aao6691|hdl=10919/84444 |hdl-access=free}}</ref>
| image = 20210000 Lobopodia lobopodians lobopods.png
| image_caption = Reconstruction of various lobopodians. 1: ''[[Microdictyon]] sinicum'', 2: ''[[Diania]] cactiformis'', 3: ''[[Collinsovermis]] monstruosus'', 4: ''[[Luolishania]] longicruris'', 5: ''[[Onychodictyon]] ferox'', 6: ''[[Hallucigenia]] sparsa'', 7: ''[[Aysheaia]] pedunculata'', 8: ''[[Antennacanthopodia]] gracilis'', 9: ''[[Facivermis]] yunnanicus'', 10: ''[[Paucipodia]] inermis'', 11: ''[[Jianshanopodia]] decora'', 12: ''[[Hallucigenia]] fortis''
| auto = yes
| display_parents = 7
| taxon = Lobopodia
| authority = Snodgrass 1938
| includes = * † "Xenusia"
** {{extinct}} [[Luolishaniidae]]
** {{extinct}} [[Hallucigeniidae]]
** {{extinct}} [[Aysheaiidae]]
** {{extinct}} [[Paucipodiidae]]
* † ''[[Pambdelurion]]'' and † [[Kerygmachelidae]]<br/>(excluded in some usages)
* [[Onychophora]] <br/>(in some usages)
* [[Tardigrada]] <br/>(in some usages)
* [[Arthropoda]]<br/>(in some usages)
| excludes = Crown-group [[Euarthropoda]]
| synonyms = {{Plainlist|
* Lobopoda <small>[[Thomas Cavalier-Smith|Cavalier-Smith]] (1998)</small>}}
}}

'''Lobopodians''' are members of the informal group '''Lobopodia'''<ref>{{cite journal |author=Snodgrass, R.E. |year=1938 |url=https://www.biodiversitylibrary.org/item/35648#page/1/mode/1up |title=Evolution of the Annelida, Onychophora, and Arthropoda |journal=Smithsonian Miscellaneous Collections |volume=97 |issue=6 |pages=1–159}}</ref> (from the [[Greek language|Greek]], meaning "blunt feet"), or the formally erected phylum '''Lobopoda''' Cavalier-Smith (1998).<ref name="Cavalier-Smith">{{cite journal |last=Cavalier-Smith |first=T. |year=1998 |title=A revised six-kingdom system of life |journal=Biological Reviews |language=en |volume=73 |issue=3 |pages=203–266 |doi=10.1017/S0006323198005167|doi-broken-date=2024-11-12 |pmid=9809012}}</ref> They are [[panarthropods]] with stubby legs called '''lobopods''',<ref name=":0">{{cite journal |last=Ortega-Hernández |first=Javier |date=2015-10-05 |title=Lobopodians |journal=Current Biology |language=en |volume=25 |issue=19 |pages=R873–R875 |doi=10.1016/j.cub.2015.07.028 |issn=0960-9822 |pmid=26439350|doi-access=free}}</ref> a term which may also be used as a common name of this group as well.<ref name=":16">{{cite journal |last1=Budd |first1=Graham |last2=Peel |first2=John |date=1998-12-01 |title=A new Xenusiid lobopod from the early Cambrian Sirius Passet fauna of North Greenland |url=https://www.palass.org/publications/palaeontology-journal/archive/41/6/article_pp1201-1213 |journal=Palaeontology |volume=41 |pages=1201–1213}}</ref><ref name="Liu2006"/> While the definition of lobopodians may differ between literatures,<ref name=":8" /> it usually refers to a group of soft-bodied, marine worm-like fossil panarthropods such as ''[[Aysheaia]]'' and ''[[Hallucigenia]]''. However, other genera like ''[[Kerygmachela]]'' and ''[[Pambdelurion]]'' (which have features similar to other groups) are often referred to as “gilled lobopodians”. <ref>{{Cite journal|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/abs/pii/S003101821300285X|journal=Palaeogeography, Palaeoclimatology, Palaeoecology|language=en|volume=398|pages=4–15|doi=10.1016/j.palaeo.2013.06.008|issn=0031-0182|last1=Liu|first1=Jianni|last2=Dunlop|first2=Jason A.|bibcode=2014PPP...398....4L}}</ref><ref name=":0" /><ref name=":13" />

The oldest near-complete [[fossil]] lobopodians date to the [[Lower Cambrian]]; some are also known from [[Ordovician]], [[Silurian]] and [[Carboniferous]] [[Lagerstätten]].<ref>{{cite journal |doi=10.1038/nature09038 |title=Ordovician faunas of Burgess Shale type |year=2010 |last1=van Roy |first1=P. |last2=Orr |first2=P.J. |last3=Botting |first3=J.P. |last4=Muir |first4=L.A. |last5=Vinther |first5=J. |last6=Lefebvre |first6=B. |last7=Hariri |first7=K.E. |last8=Briggs |first8=D.E.G. |journal=Nature |volume=465 |pages=215–218 |pmid=20463737 |issue=7295 |bibcode=2010Natur.465..215V|s2cid=4313285}}</ref><ref name="vonBitter2007">{{cite journal |first1=P.H. |last1=von Bitter |first2=M.A. |last2=Purnell |first3=D.K. |last3=Tetreault |first4=C.A. |last4=Stott |title=Eramosa Lagerstätte—Exceptionally preserved soft-bodied biotas with shallow-marine shelly and bioturbating organisms (Silurian, Ontario, Canada) |journal=Geology |volume=35 |issue=10 |pages=879 |year=2007 |doi=10.1130/G23894A.1 |bibcode=2007Geo....35..879V |s2cid=11561169}}</ref><ref name=":35">{{cite journal |last1=Haug |first1=J.T. |last2=Mayer |first2=G. |last3=Haug |first3=C. |last4=Briggs |first4=D.E.G. |title=A Carboniferous non-Onychophoran Lobopodian reveals long-term survival of a Cambrian morphotype |doi=10.1016/j.cub.2012.06.066 |journal=Current Biology |year=2012 |pmid=22885062 |volume=22 |issue=18 |pages=1673–1675|doi-access=free}}</ref> Some bear toughened claws, plates or spines, which are commonly preserved as [[small carbonaceous fossil|carbonaceous]] or [[Small Shelly Fossils|mineralized]] [[microfossils]] in Cambrian strata.<ref name=":15">{{cite journal
 | last1 = Caron  |first1 = J.-B.
 | last2 = Smith  |first2 = M.R.
 | last3 = Harvey |first3 = T.H.P.
 | year  = 2013
 | title = Beyond the Burgess Shale: Cambrian microfossils track the rise and fall of hallucigeniid lobopodians.
 | journal = Proceedings of the Royal Society B: Biological Sciences
 | volume = 280
 | issue = 1767
 | pages = 20131613
 | doi = 10.1098/rspb.2013.1613
 | pmid = 23902914
 | pmc = 3735267
}}</ref><ref name=":26">{{cite journal|last1=Topper|first1=T.P.|last2=Skovsted|first2=C.B.|last3=Peel|first3=J.S.|last4=Harper|first4=D.A.T.|author-link4=David Harper (palaeontologist)|year=2013|title=Moulting in the lobopodian ''Onychodictyon'' from the lower Cambrian of Greenland|url=https://www.academia.edu/13105212|journal=Lethaia|volume=46|issue=4|pages=490–495|doi=10.1111/let.12026}}</ref> The grouping is considered to be [[paraphyletic]], as the three living panarthropod groups ([[Arthropoda]], [[Tardigrada]] and [[Onychophora]]) are thought to have evolved from lobopodian ancestors.

== Definitions ==
[[File:20210817 Lobopodia Lobopodian Lobopod definitions.png|thumb|left|300px|Various definitions of lobopodians within [[Panarthropoda]].<ref name=":8" />]]

The Lobopodian concept varies from author to author.<ref name=":8" /> Its most general sense refers to a suite of mainly [[Cambrian]] worm-like panarthropod taxa possessing lobopods – for example, ''[[Aysheaia]]'', ''[[Hallucigenia]]'', and ''[[Xenusion]]'' – which were traditionally united as "Xenusians" or "Xenusiids" (class Xenusia).<ref name=":19" /><ref name=":30" /><ref name=":31">{{Cite journal|last1=HOU|first1=XIANGUANG|last2=BERGSTRÖM|first2=JAN|date=1995-05-01|title=Cambrian lobopodians-ancestors of extant onychophorans?|url=https://doi.org/10.1111/j.1096-3642.1995.tb00110.x|journal=Zoological Journal of the Linnean Society|volume=114|issue=1|pages=3–19|doi=10.1111/j.1096-3642.1995.tb00110.x|issn=0024-4082}}</ref> Certain [[Dinocaridida|Dinocaridid]] genera, such as ''[[Opabinia]]'', ''[[Pambdelurion]]'', and ''[[Kerygmachela]]'', may also be regarded as lobopodians,<ref name=":1">{{cite journal|last=Budd|first=Graham E.|year=1998|title=The morphology and phylogenetic significance of ''Kerygmachela kierkegaardi'' Budd (Buen Formation, Lower Cambrian, N Greenland)|journal=Earth and Environmental Science Transactions of the Royal Society of Edinburgh|language=en|volume=89|issue=4|pages=249–290|doi=10.1017/S0263593300002418|s2cid=85645934 |issn=1473-7116}}</ref><ref name=":13"/> sometimes referred to more specifically as "gilled lobopodians" or "gilled lobopods".<ref name=":18">{{Cite journal |last=Budd |first=Graham |date=August 1993 |title=A Cambrian gilled lobopod from Greenland |journal=Nature |language=en |volume=364 |issue=6439 |pages=709–711 |doi=10.1038/364709a0 |issn=1476-4687 |bibcode=1993Natur.364..709B|s2cid=4341971}}</ref> This traditional, informal usage of "Lobopodia" treats it as an [[evolutionary grade]], including only extinct Panarthropods near the base of [[crown group|crown]] Panarthropoda. Crown Panarthropoda comprises the three extant Panarthropod phyla – [[Onychophora]] (velvet worms), [[Tardigrada]] (waterbears), and [[Arthropoda]] (arthropods) – as well as their [[most recent common ancestor]] and all of its descendants. Thus, in this usage, Lobopodia consists of various basal Panarthropods.<ref name=":0" /><ref name="ReferenceA">{{cite journal |last1=Smith |first1=Martin R. |last2=Ortega-Hernández |first2=Javier |year=2014 |title=Hallucigenia's onychophoran-like claws and the case for Tactopoda |url=http://dro.dur.ac.uk/19108/1/19108.pdf |archive-url=https://ghostarchive.org/archive/20221010/http://dro.dur.ac.uk/19108/1/19108.pdf |archive-date=2022-10-10 |url-status=live |journal=Nature |volume=514 |issue=7522 |pages=363–366 |bibcode=2014Natur.514..363S |doi=10.1038/nature13576 |pmid=25132546|s2cid=205239797}}</ref><ref name=":2"/><ref name=":8"/><ref name=":10">{{cite journal |last1=Ortega-Hernández |first1=Javier |last2=Janssen |first2=Ralf |last3=Budd |first3=Graham E. |date=2017-05-01 |title=Origin and evolution of the panarthropod head – A palaeobiological and developmental perspective |journal=Arthropod Structure & Development|series=Evolution of Segmentation |volume=46 |issue=3 |pages=354–379 |doi=10.1016/j.asd.2016.10.011 |pmid=27989966 |issn=1467-8039|doi-access=free}}</ref><ref name=":11" /> This corresponds to "A" in the image to the left.

An alternative, broader definition of Lobopodia would also incorporate Onychophora and Tardigrada,<ref name=":19">{{cite journal |last1=Dzik |first1=Jerzy |last2=Krumbiegel |first2=Günter |date=1989 |title=The oldest 'onychophoran' Xenusion: a link connecting phyla? |journal=Lethaia |language=en |volume=22 |issue=2 |pages=169–181 |issn=1502-3931 |doi=10.1111/j.1502-3931.1989.tb01679.x}}</ref><ref name=":1"/><ref name="Cavalier-Smith"/> the two living panarthropod phyla which still bear lobopodous limbs. This definition, corresponding to "C", is a [[morphology (biology)|morphological]] one, depending on the superficial similarity of appendages (the "lobopods"). Thus, it is [[paraphyletic]], excluding the Euarthropods, which are descendants of certain Lobopodians, on the basis of their highly divergent limb morphology.<ref name=":0" /> "Lobopodia" has also been used to refer to a proposed sister [[clade]] to Arthropoda, consisting of the extant Onychophora and Tardigrada, as well as their most recent common ancestor and all of its descendants. This definition renders Lobopodia a [[monophyletic]] taxon, if indeed it is valid (that is, if Tardigrades and Onychophora are closer to one another than either is to Arthropoda), but would exclude all the Euarthropod-line taxa traditionally considered Lobopodians. Its validity is uncertain, however, as there are a number of hypotheses regarding the internal phylogeny of Panarthropoda.<ref>{{cite journal |last1=Smith |first1=Frank W. |last2=Goldstein |first2=Bob |date=2017-05-01 |title=Segmentation in Tardigrada and diversification of segmental patterns in Panarthropoda |journal=Arthropod Structure & Development |series=Evolution of Segmentation |volume=46 |issue=3 |pages=328–340 |doi=10.1016/j.asd.2016.10.005 |pmid=27725256 |issn=1467-8039}}</ref> The broadest definition treats Lobopodia as a monophyletic superphylum equivalent in [[circumscription (taxonomy)|circumscription]] to [[Panarthropoda]]. By this definition, represented by "D" in the image, Lobopodia is no longer treated as an evolutionary grade but as a clade, containing not only the early, superficially "Lobopodian" forms but also all of their descendants, including the extant Panarthropods.<ref name=":20">{{cite book |url=https://books.google.com/books?id=Pj-q9eHyIx0C&pg=PA125 |title=Arthropod Relationships |last1=Fortey |first1=Richard A. |last2=Thomas |first2=Richard H. |date=1997-12-31 |publisher=Springer Science & Business Media |isbn=978-0-412-75420-3 |language=en}}</ref><ref name=":16" />

Lobopodia has, historically, sometimes included [[Pentastomida]],<ref name=":9" /> a group of parasitic panarthropod which were traditionally thought to be a unique [[phylum]],<ref>[http://sea-entomologia.org/IDE@/revista_98B.pdf Pentastomida - Sociedad Entomológica Aragonesa]</ref><ref>[https://books.google.com/books?id=JHm9BwAAQBAJ&dq=%22Pentastomes+do+not+display+simplified+morphology+due+to+parasitism%22&pg=PA17 Treatise on Zoology - Anatomy, Taxonomy, Biology. The Crustacea, Volum 5]</ref> but revealed by subsequent [[phylogenomic]] and anatomical studies to be a highly specialized taxon of [[crustacean]]s.<ref>{{Cite journal|last1=Riley|first1=J.|last2=Banaja|first2=A. A.|last3=James|first3=J. L.|date=1978-08-01|title=The phylogenetic relationships of the pentastomida: The case for their inclusion within the crustacea|url=https://dx.doi.org/10.1016/0020-7519%2878%2990087-5|journal=International Journal for Parasitology|language=en|volume=8|issue=4|pages=245–254|doi=10.1016/0020-7519(78)90087-5|issn=0020-7519}}</ref><ref>{{Cite journal|last1=Lavrov|first1=Dennis V.|last2=Brown|first2=Wesley M.|last3=Boore|first3=Jeffrey L.|date=2004-03-07|title=Phylogenetic position of the Pentastomida and (pan)crustacean relationships|journal=Proceedings of the Royal Society of London. Series B: Biological Sciences|volume=271|issue=1538|pages=537–544|doi=10.1098/rspb.2003.2631|pmc=1691615|pmid=15129965}}</ref><ref>{{Cite journal|last1=Regier|first1=Jerome C.|last2=Shultz|first2=Jeffrey W.|last3=Zwick|first3=Andreas|last4=Hussey|first4=April|last5=Ball|first5=Bernard|last6=Wetzer|first6=Regina|last7=Martin|first7=Joel W.|last8=Cunningham|first8=Clifford W.|date=2010|title=Arthropod relationships revealed by phylogenomic analysis of nuclear protein-coding sequences|url=https://www.nature.com/articles/nature08742|journal=Nature|language=en|volume=463|issue=7284|pages=1079–1083|doi=10.1038/nature08742|pmid=20147900|bibcode=2010Natur.463.1079R|s2cid=4427443|issn=1476-4687}}</ref><ref>{{Cite journal|last1=Lozano-Fernandez|first1=Jesus|last2=Giacomelli|first2=Mattia|last3=Fleming|first3=James F|last4=Chen|first4=Albert|last5=Vinther|first5=Jakob|last6=Thomsen|first6=Philip Francis|last7=Glenner|first7=Henrik|last8=Palero|first8=Ferran|last9=Legg|first9=David A|last10=Iliffe|first10=Thomas M|last11=Pisani|first11=Davide|date=2019-08-01|title=Pancrustacean Evolution Illuminated by Taxon-Rich Genomic-Scale Data Sets with an Expanded Remipede Sampling|url=https://doi.org/10.1093/gbe/evz097|journal=Genome Biology and Evolution|volume=11|issue=8|pages=2055–2070|doi=10.1093/gbe/evz097|issn=1759-6653|pmc=6684935|pmid=31270537}}</ref><ref>{{Citation|last=Rabet|first=Nicolas|title=Crustaceans|date=2021|work=Handbook of Marine Model Organisms in Experimental Biology|pages=271–287|publisher=CRC Press|doi=10.1201/9781003217503-15|isbn=978-1-003-21750-3|s2cid=239958264|doi-access=free}}</ref>

==Representative taxa==
{{multiple image
 | align = center
 | width = 300
 | footer = ''[[Aysheaia]] pedunculata'' and ''[[Hallucigenia]] sparsa'', two of the most iconic as well as the first described<ref name=":0" /> lobopodians.
 | image1 = Aysheaia2.jpg
 | image2 = H. sparsa.jpg
}}
The better-known [[genus|genera]] include ''[[Aysheaia]]'', which was discovered in the Canadian [[Burgess Shale]], and ''[[Hallucigenia]]'', known from both the Chenjiang [[Maotianshan Shale]] and the Burgess Shale. ''Aysheaia pedunculata'' has a morphology apparently basic for lobopodians<ref name="ReferenceA"/> — for example, a significantly annulated cuticle, a terminal mouth opening, specialized frontalmost appendages, and stubby lobopods with terminal claws. ''Hallucigenia sparsa'' is famous for having a complex history of interpretation — it was originally reconstructed with long, stilt-like legs and mysterious fleshy dorsal protuberances, and was long considered a prime example of the way in which nature experimented with the most diverse and bizarre body designs during the Cambrian.<ref>{{cite book |title=Wonderful Life: The Burgess Shale and the Nature of History |author=Gould, S.J. |author-link=Stephen Jay Gould |year=1989 |publisher=W.W. Norton & Company |title-link=Wonderful Life (book) |bibcode=1989wlbs.book.....G}}{{page needed|date=September 2015}}</ref> However, further discoveries showed that this reconstruction had placed the animal upside-down: interpreting the "stilts" as dorsal spines made it clear that the fleshy "dorsal" protuberances were actually elongated lobopods. More recent reconstruction even exchanged the front and rear ends of the animal: it was revealed that the bulbous imprint previously thought to be a head was actually gut contents being expelled from the anus.<ref name=":15"/><ref name=":2">{{cite journal |last1=Smith |first1=Martin R. |last2=Caron |first2=Jean-Bernard |date=July 2015 |title=Hallucigenia's head and the pharyngeal armature of early ecdysozoans |url=https://www.researchgate.net/publication/279175919 |journal=Nature |language=en |volume=523 |issue=7558 |pages=75–78 |doi=10.1038/nature14573 |pmid=26106857 |issn=0028-0836 |bibcode=2015Natur.523...75S|s2cid=205244325}}</ref>

''[[Microdictyon]]'' is another charismatic as well as the speciose genus of lobopodians resembling ''Hallucigenia'', but instead of spines, it bore pairs of net-like plates, which are often found disarticulated and are known as an example of [[small shelly fossils]] (SSF). ''[[Xenusion]]'' has the oldest fossil record amongst the described lobopodians, which may trace back to [[Cambrian Stage 2]].<ref name=":19"/><ref name=":13"/> ''[[Luolishania]]'' is an iconic example of lobopodians with multiple pairs of specialized appendages.<ref name=":4"/> The gill lobopodians ''[[Kerygmachela]]'' and ''[[Pambdelurion]]'' shed light on the relationship between lobopodians and [[arthropod]]s, as they have both lobopodian affinities and characteristics linked to the arthropod stem-group.<ref name=":18"/><ref name=":20"/>

==Morphology==
[[File:Aysheaia Walcott 1911.png|thumb|140px|Complete fossil of ''[[Aysheaia]] pedunculata'', showing overall morphology.]]
<gallery mode="packed" heights="200">
File:20210000 Hallucigenia diagrammatic reconstruction.png|Maximum size of the 3 species of ''[[Hallucigenia]]'' (from top, ''H. fortis'', ''H. hongmeia'' and ''H. sparsa'') in scale.
File:Xenusion auerswaldae.jpg|Fossils of ''[[Xenusion]]'', a lobopodian that might have grown up to 20&nbsp;centimeters. 
</gallery>

Most lobopodians were only a few centimeters in length, while some genera grew up to over 20&nbsp;centimeters.<ref name="Liu2006"/> Their bodies are [[Annulus (zoology)|annulated]], although the presence of annulation may differ between position or taxa, and sometimes difficult to discern due to their close spacing and low relief on the fossil materials.<ref name='Hou2004'/> Body and appendages are circular in cross-section.<ref name='Hou2004'/>

=== Head ===
{{multiple image
| align = right
| width = 220
| footer = 
| image1 = 20210822 Onychodictyon ferox anterior.png
| caption1 = Anterior section of ''[[Onychodictyon]] ferox'', showing head structures.
| image2 = Jianshanopodia decora 1.jpg
| caption2 = Fossil of ''[[Jianshanopodia]] decora'', showing head region (upper left) compose of robust frontal appendage (right) and pharynx with rows of teeth (bottom left).
}}

Due to the usually poor preservation, detailed reconstructions of the head region are only available for a handful of lobopodian species.<ref name=":22" /><ref name=":2" /> The head of a lobopodian is more or less bulbous,<ref name=":0" /> and sometime possesses a pair of pre-ocular, presumely protocerebral<ref name=":10" /> appendages – for example, primary antennae<ref name=":3" /><ref name=":4">{{cite journal|last1=Ma|first1=Xiaoya|last2=Hou|first2=Xianguang|last3=Bergström|first3=Jan|year=2009|title=Morphology of ''Luolishania longicruris'' (Lower Cambrian, Chengjiang Lagerstätte, SW China) and the phylogenetic relationships within lobopodians|url=https://www.academia.edu/4124153|journal=Arthropod Structure & Development|language=en|volume=38|issue=4|pages=271–291|doi=10.1016/j.asd.2009.03.001|issn=1467-8039|pmid=19293001}}</ref><ref name=":10" /><ref name=":28" /> or well-developed frontal appendages,<ref name=":32">{{Cite journal|last=Whittington|first=Harry Blackmore|date=1978-11-16|title=The Lobopod Animal ''Aysheaia Pedunculata'' Walcott, Middle Cambrian, Burgess Shale, British Columbia|url=https://royalsocietypublishing.org/doi/10.1098/rstb.1978.0061|journal=Philosophical Transactions of the Royal Society of London. B, Biological Sciences|volume=284|issue=1000|pages=165–197|doi=10.1098/rstb.1978.0061|bibcode=1978RSPTB.284..165W}}</ref><ref name=":1" /><ref name="Liu2007" /><ref name="Liu2006" /><ref name=":0"/> which are individualized from the trunk lobopods<ref name=":10" /><ref name=":21">{{Cite journal |last=Jockusch |first=Elizabeth L. |date=2017-09-01 |title=Developmental and Evolutionary Perspectives on the Origin and Diversification of Arthropod Appendages |journal=Integrative and Comparative Biology |language=en |volume=57 |issue=3 |pages=533–545 |doi=10.1093/icb/icx063 |pmid=28957524 |issn=1540-7063|doi-access=free}}</ref> (with the exception of ''[[Antennacanthopodia]]'', which have two pairs of head appendages instead of one<ref name=":3" />). Mouthparts may consist of rows of teeth<ref name="Hou2004"/><ref name=":2"/><ref name="Liu2007" /><ref name="Liu2006" /><ref name=":7">{{Cite journal|last1=Vinther|first1=Jakob|last2=Porras|first2=Luis|last3=Young|first3=Fletcher|last4=Budd|first4=Graham|last5=Edgecombe|first5=Gregory|date=2016-09-01|title=The mouth apparatus of the Cambrian gilled lobopodian ''Pambdelurion whittingtoni''|url=https://www.researchgate.net/publication/309090813|journal=Palaeontology|volume=59|issue=6|pages=841–849|doi=10.1111/pala.12256|bibcode=2016Palgy..59..841V |hdl=1983/16da11f1-5231-4d6c-9968-69ddc5633a8a|s2cid=88758267 |hdl-access=free}}</ref> or a conical proboscis.<ref name=":22">{{Cite journal |last1=Ou |first1=Qiang |last2=Shu |first2=Degan |last3=Mayer |first3=Georg |date=2012-12-11 |title=Cambrian lobopodians and extant onychophorans provide new insights into early cephalization in Panarthropoda |journal=Nature Communications |language=en |volume=3 |issue=1 |pages=1261 |doi=10.1038/ncomms2272 |pmid=23232391 |pmc=3535342 |issn=2041-1723 |bibcode=2012NatCo...3.1261O}}</ref><ref name=":0" /><ref name=":6" /> The eyes may be represented by a single ocellus or by numerous<ref name=":23" /> pairs of simple ocelli,<ref name=":0" /> as has been shown in ''[[Luolishania]]''<ref name=":4" /> (=''[[Miraluolishania]]''<ref name=":23">{{Cite journal|last1=Schoenemann|first1=Brigitte|last2=Liu|first2=Jian-Ni|last3=Shu|first3=De-Gan|last4=Han|first4=Jian|last5=Zhang|first5=Zhi-Fei|date=2009|title=A miniscule optimized visual system in the Lower Cambrian|journal=Lethaia|language=en|volume=42|issue=3|pages=265–273|doi=10.1111/j.1502-3931.2008.00138.x|issn=1502-3931}}</ref><ref name=":27" />), ''[[Ovatiovermis]]'',<ref name=":6" /> ''[[Onychodictyon]]'',<ref name=":22" /> ''[[Hallucigenia]]'',<ref name=":2" /> ''[[Facivermis]]'',<ref name=":27" /> and less certainly ''[[Aysheaia]]'' as well.<ref name=":22" /> However, in gilled lobopodians like ''[[Kerygmachela]]'', the eyes are relatively complex reflective patches<ref>{{Cite journal|last1=Fleming|first1=James F.|last2=Kristensen|first2=Reinhardt Møbjerg|last3=Sørensen|first3=Martin Vinther|last4=Park|first4=Tae-Yoon S.|last5=Arakawa|first5=Kazuharu|last6=Blaxter|first6=Mark|last7=Rebecchi|first7=Lorena|last8=Guidetti|first8=Roberto|last9=Williams|first9=Tom A.|last10=Roberts|first10=Nicholas W.|last11=Vinther|first11=Jakob|date=2018-12-05|title=Molecular palaeontology illuminates the evolution of ecdysozoan vision|journal=Proceedings of the Royal Society B: Biological Sciences|volume=285|issue=1892|pages=20182180|doi=10.1098/rspb.2018.2180|issn=0962-8452|pmc=6283943|pmid=30518575}}</ref> that may had been [[Compound eye|compound]] in nature.<ref name=":14">{{Cite journal|last1=Park|first1=Tae-Yoon S.|last2=Kihm|first2=Ji-Hoon|last3=Woo|first3=Jusun|last4=Park|first4=Changkun|last5=Lee|first5=Won Young|last6=Smith|first6=M. Paul|last7=Harper|first7=David A. T.|last8=Young|first8=Fletcher|last9=Nielsen|first9=Arne T.|date=2018-03-09|title=Brain and eyes of ''Kerygmachela'' reveal protocerebral ancestry of the panarthropod head|journal=Nature Communications|language=En|volume=9|issue=1|pages=1019|bibcode=2018NatCo...9.1019P|doi=10.1038/s41467-018-03464-w|issn=2041-1723|pmc=5844904|pmid=29523785}}</ref>

=== Trunk and lobopods ===
{{multiple image
| align = right
| width = 220
| footer = 
| image1 = 20210829 Paucipodia inermis diagrammatic reconstruction.png
| caption1 = ''[[Paucipodia]] inermis'', a lobopodian with featureless, undifferentiated trunk region.
| image2 = 20210902 Luolishania longicruris Miraluolishania haikouensis diagrammatic reconstruction.png
| caption2 = ''[[Luolishania]] longicruris'', showing clear differentiation between trunk segments and lobopods.
}}

The trunk is elongated and composed of numerous body segments ([[somites]]), each bearing a pair of legs called lobopods<ref name=":0" /> or lobopodous limbs.<ref name=":1" /> The segmental boundaries are not as externally significant as those of arthropods, although they are indicated by heteronomous annulations (i.e., the alternation of annulation density corresponding to the position of segmental boundaries) in some species.<ref name=":33">Chen, J.Y., Zhou, G.Q., Ramsköld, L. (1995a). [https://www.academia.edu/3776072 The Cambrian lobopodian ''Microdictyon sinicum'']. Bulletin of the National Museum of Natural Science 5, 1–93 (Taichung, Taiwan).</ref><ref name=":4" /><ref name="ReferenceA" /> The trunk segments may bear other external, segment-corresponding structures such as nodes (e.g. ''[[Hadranax]]'',<ref name=":16" /> ''[[Kerygmachela]]''<ref name=":1" />), papillae (e.g. ''[[Onychodictyon]]''<ref name=":22" />), spine/plate-like sclerites (e.g. armoured lobopodians<ref name=":0" />) or lateral flaps (e.g. gilled lobopodians<ref name=":1" /><ref name=":7" />). The trunk may terminate with a pair of lobopods (e.g. ''[[Aysheaia]]'', ''[[Hallucigenia]] sparsa'')<ref name=":2" /> or a tail-like extension (e.g. ''[[Paucipodia]]'', ''[[Siberion]]'', ''[[Jianshanopodia]]'').<ref name=":33" /><ref name="Hou2004" /><ref name="Liu2006" /><ref name=":9" />

The lobopods are flexible and loosely conical in shape, tapering from the body to tips that may <ref name="ReferenceA" /><ref name=":0" /> or may not <ref name=":3">{{cite journal |last1=Ou |first1=Qiang |last2=Liu |first2=Jianni |last3=SHU |first3=DEGAN |last4=Han |first4=Jian |last5=Zhang |first5=Zhifei |last6=Wan |first6=Xiaoqiao |last7=Lei |first7=Qianping |date=2011-05-01 |title=A Rare Onychophoran-Like Lobopodian from the Lower Cambrian Chengjiang Lagerstätte, Southwestern China, and its Phylogenetic Implications |url=https://www.researchgate.net/publication/259887599 |journal=Journal of Paleontology |volume=85 |issue=3 |pages=587–594 |doi=10.1666/09-147R2.1 |jstor=23020193|bibcode=2011JPal...85..587O |s2cid=53056128}}</ref><ref name=":12">{{cite journal|last1=Ma|first1=Xiaoya|last2=Edgecombe|first2=Gregory|last3=Legg|first3=David|last4=Hou|first4=Xianguang|date=2013-05-08|title=The morphology and phylogenetic position of the Cambrian lobopodian ''Diania cactiformis''|url=https://www.researchgate.net/publication/247777382|journal=Journal of Systematic Palaeontology|volume=12|issue=4|pages=445–457|doi=10.1080/14772019.2013.770418|s2cid=220463025}}</ref><ref name=":13">{{cite journal|last1=Ou|first1=Qiang|last2=Mayer|first2=Georg|date=2018-12-01|title=A Cambrian unarmoured lobopodian, †''Lenisambulatrix humboldti'' gen. et sp. nov., compared with new material of †''Diania cactiformis''|url=https://www.researchgate.net/publication/327777757|journal=Scientific Reports|volume=8|issue=1|pages=13667|bibcode=2018NatSR...813667O|doi=10.1038/s41598-018-31499-y|pmc=6147921|pmid=30237414|doi-access=free}}</ref> bear claws. The claws, if present, are hardened structures with a shape resembling a hook or gently-curved spine.<ref name="Hou2004" /><ref name=":36">{{Cite journal|last1=Steiner|first1=M.|last2=Hu|first2=S.X.|last3=Liu|first3=J.|last4=Keupp|first4=H.|date=2012-02-02|title=A new species of ''Hallucigenia'' from the Cambrian Stage 4 Wulongqing Formation of Yunnan (South China) and the structure of sclerites in lobopodians|journal=Bulletin of Geosciences|pages=107–124|doi=10.3140/bull.geosci.1280|issn=1802-8225|doi-access=free}}</ref><ref name=":4" /><ref name="ReferenceA" /><ref name=":0" /> Claw-bearing lobopods usually have two claws, but single claws are known (e.g. posterior lobopods of [[luolishaniids]]<ref name=":4" /><ref name=":6" /><ref name=":28" />), as are more than two (e.g. three in ''[[Tritonychus]]'',<ref name=":34" /> seven in ''[[Aysheaia]]''<ref name=":32" />) depending on its segmental or taxonomical association.<ref name="ReferenceA" /> In some genera, the lobopods bear additional structures such as spines (e.g. ''[[Diania]]''<ref name=":12" />), fleshy outgrowths (e.g. ''[[Onychodictyon]]''<ref name=":22" />), or tubercules (e.g. ''[[Jianshanopodia]]''<ref name="Liu2006" />). There is no sign of [[Arthropod leg|arthropodization]] (development of a hardened exoskeleton and segmental division on panarthropod appendages) in known members of lobopodians, even for those belonging to the [[arthropod]] stem-group (e.g. gilled lobopodians and siberiids), and the suspected case of arthropodization on the limbs of ''[[Diania]]''<ref name=":24">{{cite journal |last1=Liu |first1=Jianni |last2=Steiner |first2=Michael |last3=Dunlop |first3=Jason A. |last4=Keupp |first4=Helmut |last5=Shu |first5=Degan |last6=Ou |first6=Qiang |last7=Han |first7=Jian |last8=Zhang |first8=Zhifei |last9=Zhang |first9=Xingliang |date=February 2011 |title=An armoured Cambrian lobopodian from China with arthropod-like appendages |journal=Nature |language=en |volume=470 |issue=7335 |pages=526–530 |doi=10.1038/nature09704 |pmid=21350485 |issn=1476-4687 |bibcode=2011Natur.470..526L|s2cid=4324509}}</ref> is considered to be a misinterpretation.<ref name=":12" /><ref name=":13" />

Differentiation (tagmosis) between trunk somites barely occurs, except in [[hallucigenids]] and luolishaniids, where numerous pairs of their anterior lobopods are significantly slender (hallucigenids) or setose (luolishaniids) in contrast to their posterior counterparts.<ref name=":0" /><ref name=":2" /><ref name=":6" /><ref name=":11" /><ref name=":28" />

=== Internal structures ===

[[File:Jianshanopodia decora.jpg|thumb|Fossilized posterior trunk region of ''[[Jianshanopodia]] decora'', showing traces of lobopods, gut diverculae and lobe-like terminal extension.]]

The gut of lobopodians is often straight, undifferentiated,<ref name=":5">{{Cite journal|last1=Vannier|first1=Jean|last2=Liu|first2=Jianni|last3=Lerosey-Aubril|first3=Rudy|last4=Vinther|first4=Jakob|last5=Daley|first5=Allison C.|date=2014-05-02|title=Sophisticated digestive systems in early arthropods|journal=Nature Communications|language=en|volume=5|issue=1|pages=3641|doi=10.1038/ncomms4641|pmid=24785191|issn=2041-1723|bibcode=2014NatCo...5.3641V|doi-access=free}}</ref> and sometimes preserved in the fossil record in three dimensions. In some specimens the gut is found to be filled with sediment.<ref name="Hou2004">{{cite journal|author=Hou, Xian-Guang|last2=Ma|first2=Xiao-Ya|last3=Zhao|first3=Jie|last4=Bergström|first4=Jan|year=2004|title=The lobopodian ''Paucipodia inermis'' from the Lower Cambrian Chengjiang fauna, Yunnan, China|url=https://www.academia.edu/4190258|journal=Lethaia|volume=37|issue=3|pages=235–244|doi=10.1080/00241160410006555}}</ref> The gut consists of a central tube occupying the full length of the lobopodian's trunk,<ref name="Liu2006">{{cite journal |title=A large xenusiid lobopod with complex appendages from the Lower Cambrian Chengjiang Lagerstätte|author1=Jianni Liu |author2=Degan Shu |author3=Jian Han |author4=Zhifei Zhang |author5=Xingliang Zhang  |name-list-style=amp |journal=Acta Palaeontol. Pol. |volume=51 |issue=2 |pages=215–222 |year=2006 |url=http://www.app.pan.pl/archive/published/app51/app51-215.pdf |archive-url=https://ghostarchive.org/archive/20221010/http://www.app.pan.pl/archive/published/app51/app51-215.pdf |archive-date=2022-10-10 |url-status=live |access-date=9 February 2011}}</ref> which does not change much in width - at least not systematically. However, in some groups, specifically the gilled lobopodians and siberiids, the gut is surrounded by pairs of serially repeated, kidney-shaped gut diverticulae (digestive glands).<ref name="Liu2006" /><ref name="Liu2007">{{cite journal| first1 = J. |first2=D. |first3=J. |first4=Z. | first5=X. |title=Morpho-anatomy of the lobopod Magadictyon cf. Haikouensis from the Early Cambrian Chengjiang Lagerstätte, South China |journal=Acta Zoologica |volume=88 |issue=4 |pages=279–288 |year=2007 |last1=Liu |doi=10.1111/j.1463-6395.2007.00281.x |last2=Shu |last3=Han |last4=Zhang |last5=Zhang}}</ref><ref name=":5" /> In some specimens, parts of the lobopodian gut can be preserved in three dimensions. This cannot result from phosphatisation, which is usually responsible for 3-D gut preservation,<ref name="LeancholiaGuts">{{cite journal |first1=N. J. |title=Leanchoilia guts and the interpretation of three-dimensional structures in Burgess Shale-type fossils |journal=Paleobiology |volume=28 |pages=155–171 |year=2002 |issn=0094-8373 |last1=Butterfield |doi=10.1666/0094-8373(2002)028<0155:LGATIO>2.0.CO;2 |s2cid=85606166}}</ref> because the phosphate content of the guts is under 1%; the contents comprise quartz and muscovite.<ref name="Hou2004" /> The gut of the representative ''[[Paucipodia]]'' is variable in width, being widest at the centre of the body. Its position in the body cavity is only loosely fixed, so flexibility is possible.

[[File:20191029 Kerygmachela brain and digestive system.png|thumb|Eyes (deep blue), brain (light blue) and digestive system (yellow) of ''[[Kerygmachela]]''.]]

Not much is known about the neural anatomy of lobopodians due to the spare and mostly ambiguous fossil evidence. Possible traces of a nervous system were found in ''[[Paucipodia]]'', ''[[Megadictyon]]'' and ''[[Antennacanthopodia]]''.<ref name="Liu2007" /><ref name="Hou2004" /><ref name=":3" /> The first and so far the only confirmed evidence of lobopodian neural structures comes from the gilled lobopodian ''[[Kerygmachela]]'' in Park et al. 2018 — it presents a brain composed of only a protocerebrum (the frontal-most cerebral [[ganglion]] of [[panarthropods]]) that is directly connected to the nerves of eyes and frontal appendages, suggesting the protocerebral ancestry of the head of lobopodians as well as the whole [[Panarthropoda]].<ref name=":14" />

In some extant [[ecdysozoa]]n such as [[priapulid]]s and [[onychophora]]ns, there is a layer of outermost circular muscles and a layer of innermost longitudinal muscles. The onychophorans also have a third, intermediate, layer of interwoven oblique muscles. Musculature of the gilled lobopodian ''[[Pambdelurion]]'' shows a similar anatomy,<ref name=":29" /> but that of the lobopodian ''[[Tritonychus]]'' shows the opposite pattern: it is the outermost muscles that are longitudinal and the innermost layer that consists of circular muscles.<ref name=":34">{{Cite journal|last1=Zhang|first1=Xi-Guang|last2=Smith|first2=Martin R.|last3=Yang|first3=Jie|last4=Hou|first4=Jin-Bo|date=2016|title=Onychophoran-like musculature in a phosphatized Cambrian lobopodian|journal=Biology Letters|language=en|volume=12|issue=9|pages=20160492|doi=10.1098/rsbl.2016.0492|pmid=27677816|pmc=5046927|issn=1744-9561}}</ref>

== Categories ==

Based on external morphology, lobopdians may fall under different categories — for example the general worm-like taxa as "xenusiid" or "xenusian"; xenusiid with sclerite as "armoured lobopodians"; and taxa with both robust frontal appendages and lateral flaps as "gilled lobopodians". Some of them were originally defined under a taxonomic sense (e.g. class Xenusia), but neither any of them are generally accepted as [[monophyletic]] in further studies.<ref name="ReferenceA" /><ref name=":8" /><ref name=":10" />

=== Armoured lobopodians ===

{{multiple image
| align = right
| width = 220
| footer = 
| image1 = MICRODICTYON SINICUM.jpg
| caption1 = Fossil of ''[[Microdictyon]] sinicum'', showing pairs of sclerite and trace of trunk and lobopods.
| image2 = 20210429 Diania cactiformis diagrammatic reconstruction.png
| caption2 = ''[[Diania]] cactiformis'', an armoured lobopodian covered by myriad spines.
}}

Armoured lobopodians referred to [[xenusiid]] lobopodians which bore repeated sclerites such as spine or plates on their trunk (e.g. ''[[Hallucigenia]]'', ''[[Microdictyon]]'', ''[[Luolishania]]'') or lobopods (e.g. ''[[Diania]]''). In contrast, lobopodians without sclerites may be referred to as "unarmoured lobopodians".<ref name=":3" /><ref name=":13" /> Function of the sclerites were interpreted as protective armor and/or muscle attachment points.<ref name=":33" /><ref name="Budd2001" /><ref name=":0" /> In some cases, only the disarticulated sclerites of the animal were preserved, which represented as component of [[small shelly fossils]] (SSF).<ref name=":33" /><ref name=":15" /> Armoured lobopodians were suggest to be onychophoran-related and may even represent a [[clade]] in some previous studies,<ref name="Budd2001" /> but their phylogenetic positions in later studies are controversial. ([[#As stem-group onychophorans|see text]])

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=== Gilled lobopodians ===

[[File:20210730 Gilled lobopodians Pambdelurion Kerygmachela.png|thumb|The gilled lobopodians ''[[Pambdelurion]]'' (top left) and ''[[Kerygmachela]]'' (bottom right).]]

[[dinocaridida|Dinocaridids]] with lobopodian affinities (due to shared features like annulation and lobopods) are referred to as "gilled lobopodians"<ref name=":8" /><ref name=":7" /><ref name=":29" /> or "gilled lobopods".<ref name=":18" /> These forms sport a pair of flaps on each trunk segment, but otherwise no signs of arthropodization, in contrast to more derived dinocaridids like the [[Radiodonta]] that have robust and sclerotized frontal appendages. Gilled lobopodians cover at least four genera: ''[[Pambdelurion]]'', ''[[Kerygmachela]]'', ''[[Utahnax]]'' and ''[[Mobulavermis]]''.<ref name=":13" /><ref>{{Cite journal |last=McCall |first=C. R. A. |year=2023 |title=A large pelagic lobopodian from the Cambrian Pioche Shale of Nevada |journal=Journal of Paleontology |volume=97 |issue=5 |pages=1009–1024 |doi=10.1017/jpa.2023.63}}</ref> ''[[Opabinia]]'' may also fall under this category in a broader sense,<ref name=":8">{{Cite journal|last=Ortega-Hernández|first=Javier|date=December 2014|title=Making sense of 'lower' and 'upper' stem-group Euarthropoda, with comments on the strict use of the name Arthropoda von Siebold, 1848|journal=Biological Reviews of the Cambridge Philosophical Society|volume=91|issue=1|pages=255–273|doi=10.1111/brv.12168|issn=1469-185X|pmid=25528950|s2cid=7751936}}</ref><ref name=":17">{{Cite journal|last1=Van Roy|first1=Peter|last2=Daley|first2=Allison C.|last3=Briggs|first3=Derek E. G.|date=2015|title=Anomalocaridid trunk limb homology revealed by a giant filter-feeder with paired flaps|journal=Nature|language=en|volume=522|issue=7554|pages=77–80|doi=10.1038/nature14256|pmid=25762145|issn=1476-4687|bibcode=2015Natur.522...77V|s2cid=205242881}}</ref> although the presence of lobopods in this genus is not definitively proven.<ref>{{Cite journal|last1=Budd|first1=Graham E.|last2=Daley|first2=Allison C.|date=January 2012|title=The lobes and lobopods of Opabinia regalis from the middle Cambrian Burgess Shale: The lobes of Opabinia|url=https://www.academia.edu/483085|journal=Lethaia|language=en|volume=45|issue=1|pages=83–95|doi=10.1111/j.1502-3931.2011.00264.x}}</ref> ''[[Omnidens]]'', a genus known only from a ''Pambdelurion''-like mouth apparatus, may also be a gilled lobopodian.<ref name=":7" /> The body flaps may have functioned as both swimming appendages and gills,<ref name=":18" /> and are possibly homologous to the dorsal flaps of radiodonts and exites of [[euarthropods|Euarthropoda]].<ref name=":1" /><ref name=":17" /> Whether these genera were true lobopodians is still contested by some.<ref>{{Cite journal|last1=Chen|first1=J.-y|last2=Ramskold|first2=L.|last3=Zhou|first3=G.-q|title=Evidence for Monophyly and Arthropod Affinity of Cambrian Giant Predators|url=https://www.academia.edu/1781228|journal=Science|language=en|volume=264|issue=5163|pages=1304–1308|issn=0036-8075|doi=10.1126/science.264.5163.1304|bibcode=1994Sci...264.1304C|year=1994|pmid=17780848|s2cid=1913482}}</ref> However, they are widely accepted as stem-group [[arthropod]]s just basal to radiodonts.<ref name=":8" /><ref name="ReferenceA" /><ref name=":2" /><ref name=":10" />

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=== ''Siberion'' and similar taxa ===
[[File:20191217 Siberiida Siberion Megadictyon Jianshanopodia.png|thumb|The siberiid lobopodians ''[[Siberion]]'' (upper left), ''[[Megadictyon]]'' (bottom center) and ''[[Jianshanopodia]]'' (upper right).]]

''[[Siberion]]'', ''[[Megadictyon]]'' and ''[[Jianshanopodia]]'' may be grouped as siberiids (order [[Siberiida]]),<ref name=":9">{{Cite journal |last=Dzik |first=Jerzy |date=2011-07-01 |df=dmy-all |title=The xenusian-to-anomalocaridid transition within the lobopodians |url=http://paleoitalia.org/media/u/archives/7.Dzik_-_BollSPI_50-1.pdf |archive-url=https://ghostarchive.org/archive/20221010/http://paleoitalia.org/media/u/archives/7.Dzik_-_BollSPI_50-1.pdf |archive-date=2022-10-10 |url-status=live |journal=Bollettino della Societa Paleontologica Italiana |volume=50 |pages=65–74}}</ref> jianshanopodians<ref name="ReferenceA" /> or "giant lobopodians"<ref>{{Cite journal|last=Edgecombe|first=Gregory D.|date=2020-11-02|title=Arthropod Origins: Integrating Paleontological and Molecular Evidence|url=https://www.annualreviews.org/doi/10.1146/annurev-ecolsys-011720-124437|journal=Annual Review of Ecology, Evolution, and Systematics|volume=51|issue=1|pages=1–25|doi=10.1146/annurev-ecolsys-011720-124437|s2cid=225478171|issn=1543-592X}}</ref> by some literatures. They are generally large — body length ranging between 7<ref name=":9"/> and 22&nbsp;centimeters<ref name="Liu2007"/> (2¼ to 8⅔ inches) — xenusiid lobopodians with widen trunk, stout trunk lobopods without evidence of claws, and most notably a pair of robust frontal appendages.<ref name=":8"/> With the possible exception of ''Siberion'',<ref name=":9" /><ref name="ReferenceA" /> they also have digestive glands like those of a gilled lobopodian and basal euarthropod.<ref name="Liu2006" /><ref name="Liu2007" /><ref name=":8"/><ref name=":5"/> Their anatomy represent transitional forms between typical xenusiids and gilled lobopodians,<ref name=":9"/> eventually placing them under the basalmost position of arthropod stem-group.<ref name="Liu2006"/><ref name="Liu2007"/><ref name=":8"/><ref name=":10"/>
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== Paleoecology ==
{{multiple image
| align = right
| width = 220
| footer = 
| image1 = Ovatiovermis cribratus life restoration.jpg
| caption1 = Reconstruction of a [[suspension feeding|suspension-feeding]] lobopodian ''[[Ovatiovermis]] cribratus'', showing how it used the anterior 6 pairs of lobopods to gather food particles, while using the posterior 3 pairs of lobopods to anchor itself.<ref name=":6" />
| image2 = Pambdelurion whittingtoni.JPG
| caption2 = Reconstruction of the gilled lobopodian ''[[Pambdelurion]] whittingtoni'' as a [[nektonic]] [[predator]].
}}

Lobopodians possibly occupied a wide range of [[ecological niche]]s.<ref name=":0" /> Although most of them had undifferentiated appendages and straight gut, which would suggest a simple sediment-feeding lifestyle,<ref name=":0" /> sophisticated digestive glands and large size of gilled lobopodians and siberiids would allow them to consume larger food items,<ref name=":0" /><ref name=":5" /> and their robust frontal appendages may even suggest a [[predatory]] lifestyle.<ref name="Liu2006" /><ref name=":5" /> On the other hand, luolishaniids such as ''[[Luolishania]]'' and ''[[Ovatiovermis]]'' have elaborate feather-like lobopods that presumably formed 'baskets' for [[Filter feeder|suspension or filter-feeding]].<ref name=":4" /><ref name=":6">{{Cite journal|last1=Caron|first1=Jean-Bernard|last2=Aria|first2=Cédric|date=2017-01-31|title=Cambrian suspension-feeding lobopodians and the early radiation of panarthropods|journal=BMC Evolutionary Biology|volume=17|issue=1|pages=29|doi=10.1186/s12862-016-0858-y|issn=1471-2148|pmc=5282736|pmid=28137244 |doi-access=free |bibcode=2017BMCEE..17...29C}}</ref> Lobopods with curved terminal claws may have given some lobopodians the ability to climb on substrances.<ref name=":0" />

Not much is known about the [[physiology]] of lobopodians. There is evidence to suggest that lobopodians [[moult]] just like other [[ecdysozoa]]n taxa, but the outline and ornamentation of the harden sclerite did not vary during [[ontogeny]].<ref name=":33" /><ref name=":26" /> The gill-like structures on the body flaps of gilled lobopodians and ramified extensions on the lobopods of ''[[Jianshanopodia]]'' may provide [[respiratory]] function ([[gills]]).<ref name=":18" /><ref name="Liu2006" /> ''[[Pambdelurion]]'' may control the movement of their lobopods in a way similar to [[onychophorans]].<ref name=":29">{{Cite journal|last1=Young|first1=Fletcher J.|last2=Vinther|first2=Jakob|date=2017|title=Onychophoran-like myoanatomy of the Cambrian gilled lobopodian ''Pambdelurion whittingtoni''|url=https://research-information.bris.ac.uk/ws/files/89330995/Manuscript_Palaeontology_Post_review_JV.pdf |archive-url=https://ghostarchive.org/archive/20221010/https://research-information.bris.ac.uk/ws/files/89330995/Manuscript_Palaeontology_Post_review_JV.pdf |archive-date=2022-10-10 |url-status=live|journal=Palaeontology|language=en|volume=60|issue=1|pages=27–54|doi=10.1111/pala.12269|bibcode=2017Palgy..60...27Y |hdl=1983/92180ef0-2205-4c65-9a70-90d59cfea2f4 |s2cid=55477207 |issn=1475-4983}}</ref>

==Distribution==

During the Cambrian, lobopodians displayed a substantial degree of [[biodiversity]]. One species is known from each of the [[Ordovician]] and [[Silurian]] periods,<ref name="vonBitter2007" /><ref>{{Cite journal|last1=Whittle|first1=R. J.|last2=Gabbott|first2=S. E.|last3=Aldridge|first3=R. J.|last4=Theron|first4=J.|year=2009|title=An Ordovician Lobopodian from the Soom Shale Lagerstätte, South Africa|journal=Palaeontology|volume=52|issue=3|pages=561–567|doi=10.1111/j.1475-4983.2009.00860.x|bibcode=2009Palgy..52..561W |s2cid=129609503 |doi-access=free}}</ref> with a few more known from the [[Carboniferous]] (Mazon Creek) — this represents the paucity of exceptional lagerstatten in post-Cambrian deposits.

==Phylogeny==

{{cladogram
|title=
|align= right
|caption=Neutralized phylogeny between lobopodians and other [[Ecdysozoan]] taxa.<ref name="ReferenceA" /><ref name=":8" /><ref name=":2" /><ref name=":17" /><ref name=":10" /><ref name=":6" /><ref name=":11" /> Extant panarthropod taxa are in '''bold'''. Relationship between the total-group of extant panarthropod phyla is unresolved.
|cladogram=
{{clade| style=width:45em;line-height:
|label1=<small>[[Ecdysozoa]]</small>|1={{clade
  |label1=<small>[[Cycloneuralia]]</small>|1=[[Priapulida]] [[File:Adult priapulid 2.jpg|50px]], [[Nematoda]] [[File:CelegansGoldsteinLabUNC 2.jpg|70px]] and relatives
  |label2=<small>[[Panarthropoda]]</small>|2={{clade
    |1={{clade
      |1=(Lobopodian taxa controversial)
      |2={{clade
        |1=''[[Antennacanthopodia]]'' [[File:Antennacanthopodia.jpg|80px]]
        |2=Crown-group '''[[Onychophora]]''' [[File:Velvet_worm.png|80px]]
}} }}
      |2={{clade
        |1=(Lobopodian taxa controversial)
        |2=Crown-group '''[[Tardigrada]]''' [[File:SEM image of Milnesium tardigradum in active state - journal.pone.0045682.g001-2 (white background).png|60px]]
}}
    |3=(Lobopodian taxa controversial)
      |4={{clade
        |1=''[[Megadictyon]]'' [[File:20191118_Megadictyon_cf._haikouensis.png|80px]] and ''[[Jianshanopodia]]'' [[File:20191215_Jianshanopodia_decora.png|80px]]
        |2={{clade
          |1=''[[Pambdelurion]]'' [[File:20191112_Pambdelurion_whittingtoni.png|80px]] and ''[[Kerygmachela]]'' [[File:21091022_Kerygmachela_kierkegaardi.png|80px]]
          |2={{clade
            |1=''[[Opabinia]]'' [[File:20191108_Opabinia_regalis.png|80px]]
            |2=[[Radiodonta]] [[File:20191201_Radiodonta_Amplectobelua_Anomalocaris_Aegirocassis_Lyrarapax_Peytoia_Laggania_Hurdia.png|70px]]
            |3='''[[Euarthropoda]]''' [[File:Aptostichus simus Monterey County.jpg|70 px]] [[File:Scolopendra japonica アオズムカデ 大阪府 生駒山産.jpg|80 px]] [[File:Platycheirus angustatus (Syrphidae) - (male imago), Elst (Gld), the Netherlands - 2.jpg|70 px]]
}} }} }} }} }} }} }}

The overall phylogenetic interpretation on lobopodians has changed dramatically since their discovery and first description.<ref name=":0" /> The reassignments are not only based on new fossil evidence, but also new [[Embryology|embryological]], [[Neuroanatomy|neuroanatomical]], and [[genomic]] (e.g. [[gene expression]], [[phylogenomics]]) information observed from extant [[panarthropod]] taxa.<ref name=":0" /><ref name=":10" /><ref>{{Cite journal|last=Edgecombe|first=Gregory D.|date=2009-06-01|title=Palaeontological and Molecular Evidence Linking Arthropods, Onychophorans, and other Ecdysozoa|journal=Evolution: Education and Outreach|language=en|volume=2|issue=2|pages=178–190|doi=10.1007/s12052-009-0118-3|issn=1936-6434|doi-access=free}}</ref>

Based on their apparently [[onychophoran]]-like morphology (e.g. annulated cuticle, lobopodous appendage with claws), lobopodians were originally thought to be present a group of paleozoic onychophorans.<ref>{{Cite journal|last=Robison|first=R. A.|date=1985|title=Affinities of Aysheaia (Onychophora), with Description of a New Cambrian Species|journal=Journal of Paleontology|volume=59|issue=1|pages=226–235|issn=0022-3360|jstor=1304837}}</ref><ref name=":30">{{Cite journal|last1=Ramsköld|first1=L.|last2=Xianguang|first2=Hou|date=1991|title=New early Cambrian animal and onychophoran affinities of enigmatic metazoans|journal=Nature|language=en|volume=351|issue=6323|pages=225–228|doi=10.1038/351225a0|issn=1476-4687|bibcode=1991Natur.351..225R|s2cid=4309565}}</ref><ref name=":31" /><ref>{{Cite journal|last1=Bergström|first1=J.|last2=Hou|first2=Xian-Guang|date=2001-12-01|title=Cambrian Onychophora or Xenusians|url=https://www.researchgate.net/publication/248908182|journal=Zoologischer Anzeiger|volume=240|issue=3–4|pages=237–245|doi=10.1078/0044-5231-00031}}</ref><ref name=":0" /> This interpretation was challenged after the discovery of lobopodians with [[arthropod]] and [[tardigrade]]-like characteristics,<ref name=":25">{{Cite journal|last=Budd|first=Graham E.|date=2001-01-01|title=Tardigrades as 'Stem-Group Arthropods': The Evidence from the Cambrian Fauna|journal=Zoologischer Anzeiger - A Journal of Comparative Zoology|volume=240|issue=3|pages=265–279|doi=10.1078/0044-5231-00034|issn=0044-5231}}</ref> suggesting that the similarity between lobopodians and onychophorans represents deeper [[panarthropod]] ancestral traits ([[Plesiomorphy|plesiomorphies]]) instead of onychophoran-exclusive characteristics ([[synapomorphies]]).<ref name=":11" /> For example, The British palaeontologist [[Graham Budd]] sees the Lobopodia as representing a basal grade from which the phyla Onychophora and Arthropoda arose, with ''[[Aysheaia]]'' comparable to the ancestral plan, and with forms like ''[[Kerygmachela]]'' and ''[[Pambdelurion]]'' representing a transition that, via the [[Dinocaridida|dinocaridids]], would lead to an arthropod body plan.<ref name="Budd2001">{{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> Aysheaia's surface ornamentation, if homologous with [[palaeoscolecid]] sclerites, may represent a deeper link connecting it with [[cycloneuralia]]n outgroups.<ref name="Budd2001" /> Many further studies followed and extended the idea, generally in agreement that all three panarthropod phyla have lobopodians in their stem lineages.<ref name=":0" /><ref name="ReferenceA" /><ref name=":2" /><ref name=":10" /><ref name=":6" /><ref name=":11" /> Lobopodians are thus [[paraphyletic]], and include the last common ancestor of arthropods, onychophorans and tardigrades.<ref name=":0" />

===Stem-group arthropods===

Compared to other panarthropod stem-groups, suggestion on the lobopodian members of arthropod stem-group is relatively consistent  — siberiid like ''[[Megadictyon]]'' and ''[[Jianshanopodia]]'' occupied the basalmost position, gilled lobopodians ''[[Pambdelurion]]'' and ''[[Kerygmachela]]'' branch next, and finally lead to a clade compose of ''[[Opabinia]]'', [[Radiodonta]] and Euarthropoda (crown-group arthropods).<ref name="ReferenceA" /><ref name=":8" /><ref name=":2" /><ref name=":17" /><ref name=":10" /><ref name=":6" /><ref name=":11" /> Their positions within arthropod stem-group are indicated by numerous arthropod groundplans and intermediate forms (e.g. arthropod-like digestive glands, radiodont-like frontal appendages and dorso-ventral appendicular structures link to arthropod biramous appendages).<ref name=":8" /><ref name=":10" /> Lobopodian ancestry of arthropods also reinforced by genomic studies on extant taxa — gene expression support the homology between arthropod appendages and onychophoran lobopods, suggests that modern less-segmented arthropodized appendages evolved from annulated lobopodous limbs.<ref name=":21" /> On the other hand, primary antennae and frontal appendages of lobopodians and [[dinocaridida|dinocaridids]] may be homologous to the [[Labrum (arthropod mouthpart)|labrum]]/hypostome complex of euarthropods, an idea support by their protocerebral origin<ref name=":8" /><ref name=":10" /><ref name=":14" /> and developmental pattern of the labrum of extant arthropods.<ref name=":21" /><ref name=":10" />

<gallery mode="packed" heights="160">
File:20191201 Radiodonta Amplectobelua Anomalocaris Aegirocassis Lyrarapax Peytoia Laggania Hurdia.png|[[Radiodonta|Radiodonts]] are stem-group [[arthropod]]s with gilled lobopodian-like body flaps, arthropodized frontal appendages and [[Eyestalk|stalked]] [[compound eye]]s.
File:20191112 Pambdelurion whittingtoni.png|Restoration of ''[[Pambdelurion]]'' a "gilled lobopodian" related to arthropods, which has both pairs of lobopods and lateral flaps.
</gallery>

''[[Diania]]'', a genus of armoured lobopodian with stout and spiny legs, were originally thought to be associated within the arthropod stem-group based on its apparently arthropod-like (arthropodized) trunk appendages.<ref name=":24" /> However, this interpretation is questionable as the data provided by the original description are not consistent with the suspected phylogenic relationships.<ref>{{Cite journal|last1=Mounce|first1=Ross C. P.|last2=Wills|first2=Matthew A.|date=August 2011|title=Phylogenetic position of Diania challenged|url=https://www.researchgate.net/publication/51563233|journal=Nature|language=en|volume=476|issue=7359|pages=E1; discussion E3–4|doi=10.1038/nature10266|pmid=21833044|issn=1476-4687|bibcode=2011Natur.476E...1M|s2cid=4417903|doi-access=free}}</ref><ref>{{Cite journal|last1=Legg|first1=David|last2=Ma|first2=Xiaoya|last3=Wolfe|first3=Joanna|last4=Ortega-Hernández|first4=Javier|last5=Edgecombe|first5=Gregory|last6=Sutton|first6=Mark|date=2011-08-11|title=Lobopodian phylogeny reanalysed|url=https://www.researchgate.net/publication/51563234|journal=Nature|volume=476|issue=7359|pages=E2–3; discussion E3|doi=10.1038/nature10267|pmid=21833046|bibcode=2011Natur.476Q...1L|s2cid=4310063|doi-access=free}}</ref> Further re-examination even revealed that the suspected arthropodization on the legs of ''Diania'' was a misinterpretation — although the spine may have hardened, the remaining cuticle of ''Diania''<nowiki/>'s legs were soft (not harden nor scleritzed), lacking any evidence of pivot joint and arthrodial membrane, suggest the legs are lobopods with only widely spaced annulations.<ref name=":12" /><ref name=":13" /> Thus, the re-examination eventually reject the evidence of arthropodization (sclerotization, segmentation and articulation) on the appendages as well as the fundamental relationship between ''Diania'' and arthropods.<ref name=":12" /><ref name=":13" />

===Stem-group onychophorans===

[[File:Antennacanthopodia.jpg|thumb|''[[Antennacanthopodia]] gracilis'', a lobopodian suggested to be a stem-group onychophoran.]]

While ''[[Antennacanthopodia]]'' is widely accepted as a stem-group onychophoran,<ref name="ReferenceA" /><ref name=":2" /><ref name=":34" /><ref name=":6" /><ref name=":11" /><ref name=":27" /> the position of other xenusiid genera that were previously thought to be onychophoran-related is controversial — in further studies, most of them were either suggested to be stem-group onychophorans<ref name="ReferenceA" /><ref name=":2" /><ref name=":34" /><ref name=":27" /> or basal panarthropods,<ref name=":6" /><ref name=":11">{{Cite journal|last1=Siveter|first1=Derek J.|last2=Briggs|first2=Derek E. G.|last3=Siveter|first3=David J.|last4=Sutton|first4=Mark D.|last5=Legg|first5=David|title=A three-dimensionally preserved lobopodian from the Herefordshire (Silurian) Lagerstätte, UK|journal=Royal Society Open Science|volume=5|issue=8|pages=172101|doi=10.1098/rsos.172101|pmc=6124121|pmid=30224988|year=2018}}</ref><ref name=":28" /> with a few species (''[[Aysheaia]]''<ref name=":6" /><ref name=":11" /><ref name=":28" /> or ''[[Onychodictyon]] ferox''<ref name="ReferenceA" /><ref name=":2" />) occasionally suggested to be stem-group tardigrades. A study in 2014 suggested that ''[[Hallucigenia]]'' are stem-group onychophorans based on their claws, which have overlapped internal structures resembling those of an extant onychophoran.<ref name="ReferenceA" /> This interpretation was questioned by later studies, as the structures may be a [[panarthropod]] plesiomorphy.<ref name=":11" /><ref name=":28" />

===Stem-group tardigrades===
[[Image:OrstenTardigrade.jpg|thumb|Artistic reconstruction of the “[[Orsten]]” tardigrade, a parasitic stem-lineage tardigrade, known from fossils recovered from the Cambrian Kuonamka Formation of Siberia.<ref>{{Cite journal |last1=Maas |first1=Andreas |last2=Waloszek |first2=Dieter |date=2001-01-01 |title=Cambrian Derivatives of the Early Arthropod Stem Lineage, Pentastomids, Tardigrades and Lobopodians An 'Orsten' Perspective |url=https://www.sciencedirect.com/science/article/pii/S0044523104700443 |journal=Zoologischer Anzeiger - A Journal of Comparative Zoology |language=en |volume=240 |issue=3 |pages=451–459 |doi=10.1078/0044-5231-00053 |issn=0044-5231}}</ref>]]

Lobopodian taxa of the tardigrade stem-group is unclear.<ref name=":0" /> ''[[Aysheaia]]''<ref name=":6" /><ref name=":11" /><ref name=":28" /> or ''[[Onychodictyon]] ferox''<ref name="ReferenceA" /><ref name=":2" /> had been suggest to be a possible member, based on the high claw number (in ''Aysheaia'') and/or terminal lobopods with anterior-facing claws  (in both taxa).<ref name="ReferenceA" /> Although not widely accepted, there are even suggestions that Tardigrada itself representing the basalmost panarthropod or branch between the arthropod stem-group.<ref name=":25" /> However, a paper in 2023 found luolishaniids to be the closest relatives of tardigrades using various morphological characteristics. <ref name="Kihm2023">{{cite journal |doi=10.1073/pnas.2211251120 |title=Cambrian lobopodians shed light on the origin of the tardigrade body plan |year=2023 |last1=Kihm |first1=Ji-Hoon |last2=Smith |first2=Frank W. |last3=Kim |first3=Sanghee |last4=Rho |first4=Hyun Soo |last5=Zhang |first5=Xingliang |last6=Liu |first6=Jianni |last7=Park |first7=Tae-Yoon S. |journal=Proceedings of the National Academy of Sciences |volume=120 |issue=28 |pages=e2211251120 |pmid=37399417 |doi-access=free |pmc=10334802}}</ref>

===Stem-group panarthropods===

It is unclear that which lobopodians represent members of the panarthropod stem-group, which were branched just before the last common ancestor of extant panarthropod phyla. ''[[Aysheaia]]'' may have occupied this position based on its apparently basic morphology;<ref name="Budd2001" /><ref name="ReferenceA" /><ref name=":2" /><ref name=":27" /> while other studies rather suggest luolishaniid and hallucigenid,<ref name=":6" /><ref name=":11"/><ref name=":28" /> two lobopodian taxa which had been resolved as members of stem-group onychophorans as well.<ref name=":0" /><ref name="ReferenceA" /><ref name=":2" /><ref name=":34" /><ref name=":27" />

== Described genera ==
[[File:Aysheaia pedunculata.jpg|thumb|Fossil of ''[[Aysheaia]] pedunculata''.]]
[[File:Microdictyon Chengjiang.JPG|thumb|Fossil of ''[[Microdictyon]] sinicum''.]]
[[File:Mureropodia apae - Xenusia - Lower Cambrian - Murero, Spain.jpg|thumb|Fossil of "''Mureropodia apae''", which may be in fact frontal appendage of ''[[Caryosyntrips]]'' cf. ''camurus''.]]
[[File:Facivermis 2.png|thumb|Reconstruction of ''[[Facivermis]]'', an unusual lobopodian with limbless posterior region that lived like a tube worm]]

As of 2018, over 20 lobopodian genera have been described.<ref name=":13" /> The fossil materials being described as lobopodians ''[[Mureropodia]] apae'' and ''[[Aysheaia]] prolata'' are considered to be disarticulated [[Radiodonta#Frontal appendage|frontal appendages]] of the [[Radiodonta|radiodonts]] ''[[Caryosyntrips]]'' and ''[[Stanleycaris]]'', respectively.<ref>{{Cite journal|last1=Pates|first1=Stephen|last2=Daley|first2=Allison C.|date=2017|title=Caryosyntrips: a radiodontan from the Cambrian of Spain, USA and Canada|journal=Papers in Palaeontology|language=en|volume=3|issue=3|pages=461–470|doi=10.1002/spp2.1084|s2cid=135026011 |issn=2056-2802|url=http://osf.io/5avkg/}}</ref><ref>{{Cite web|url=http://www.app.pan.pl/article/item/app003612017.html|title=Aysheaia prolata from the Utah Wheeler Formation (Drumian, Cambrian) is a frontal appendage of the radiodontan Stanleycaris - Acta Palaeontologica Polonica|website=www.app.pan.pl|language=en|access-date=2020-01-08}}</ref><ref>{{Cite web|url=http://www.app.pan.pl/article/item/app004432017.html|title=Reply to Comment on "Aysheaia prolata from the Utah Wheeler Formation (Drumian, Cambrian) is a frontal appendage of the radiodontan Stanleycaris" with the formal description of Stanleycaris - Acta Palaeontologica Polonica|website=www.app.pan.pl|language=en|access-date=2020-01-08}}</ref> ''[[Miraluolishania]]'' was suggested to be [[Synonym (taxonomy)|synonym]] of ''[[Luolishania]]'' by some studies.<ref name=":4" /><ref>{{Cite journal|last1=Liu|first1=Jianni|last2=Shu|first2=DeGan|last3=Han|first3=Jian|last4=Zhang|first4=Zhifei|date=2008-05-01|title=Comparative study of Cambrian lobopods Miraluolishania and Luolishania|url=https://www.researchgate.net/publication/238479619|journal=Chinese Science Bulletin |volume=53|issue=1|pages=87–93|doi=10.1007/s11434-007-0428-1|bibcode=2008ChSBu..53...87L|s2cid=128619311}}</ref><ref name=":27" /> The enigmatic ''[[Facivermis]]'' was later revealed to be a highly specialized genus of luolishaniid lobopodians.<ref name=":9" /><ref name=":6" /><ref name=":27">{{Cite journal|last1=Howard|first1=Richard J.|last2=Hou|first2=Xianguang|last3=Edgecombe|first3=Gregory D.|last4=Salge|first4=Tobias|last5=Shi|first5=Xiaomei|last6=Ma|first6=Xiaoya|date=2020-02-27|title=A Tube-Dwelling Early Cambrian Lobopodian|journal=Current Biology|volume=30|issue=8|pages=1529–1536.e2|language=en|doi=10.1016/j.cub.2020.01.075|pmid=32109391|issn=0960-9822|doi-access=free}}</ref>
{{div col|colwidth=21em}}
*''[[Acinocricus]]''<ref>{{Cite journal|last1=Conway Morris|first1=S.|last2=Robison|first2=Richard A.|date=1988|title=More soft-bodied animals and algae from the Middle Cambrian of Utah and British Columbia|url=https://kuscholarworks.ku.edu/handle/1808/3691|journal=University of Kansas Paleontological Contributions|language=en-US|volume=122|pages=1–48|issn=0075-5052}}</ref>
*''[[Antennacanthopodia]]''<ref name=":3" />
*''[[Aysheaia]]''<ref name=":32" />
*''[[Carbotubulus]]''<ref name=":35" />
*''[[Cardiodictyon]]''<ref name=":37">{{Cite journal|last1=Xianguang|first1=Hou|last2=Ramsköld|first2=Lars|last3=Bergström|first3=Jan|date=1991|title=Composition and preservation of the Chengjiang fauna –a Lower Cambrian soft-bodied biota|url=https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1463-6409.1991.tb00303.x|journal=Zoologica Scripta|language=en|volume=20|issue=4|pages=395–411|doi=10.1111/j.1463-6409.1991.tb00303.x|s2cid=85077111|issn=1463-6409}}</ref>
*''[[Collinsium]]''<ref>{{Cite journal|last1=Yang|first1=Jie|last2=Ortega-Hernández|first2=Javier|last3=Gerber|first3=Sylvain|last4=Butterfield|first4=Nicholas J.|last5=Hou|first5=Jin-bo|last6=Lan|first6=Tian|last7=Zhang|first7=Xi-guang|date=2015-07-14|title=A superarmored lobopodian from the Cambrian of China and early disparity in the evolution of Onychophora|journal=Proceedings of the National Academy of Sciences|language=en|volume=112|issue=28|pages=8678–8683|doi=10.1073/pnas.1505596112|issn=0027-8424|pmc=4507230|pmid=26124122|bibcode=2015PNAS..112.8678Y|doi-access=free}}</ref>
*''[[Collinsovermis]]''<ref name=":28">{{Cite journal|last1=Caron|first1=Jean-Bernard|last2=Aria|first2=Cédric|date=2020|title=The Collins' monster, a spinous suspension-feeding lobopodian from the Cambrian Burgess Shale of British Columbia|url=https://onlinelibrary.wiley.com/doi/abs/10.1111/pala.12499|journal=Palaeontology|volume=63|issue=6|pages=979–994|language=en|doi=10.1111/pala.12499|s2cid=225593728|issn=1475-4983}}</ref>
*''[[Diania]]''<ref name=":24" /><ref name=":12" />
*''[[Entothyreos]]''<ref>{{Cite journal|last1=Aria |first1=C. |last2=Caron |first2=J.-B. |year=2024 |title=Deep origin of articulation strategies in panarthropods: evidence from a new luolishaniid lobopodian (Panarthropoda) from the Tulip Beds, Burgess Shale |journal=Journal of Systematic Palaeontology |volume=22 |issue=1 |at=2356090 |doi=10.1080/14772019.2024.2356090 |bibcode=2024JSPal..2256090A}}</ref>
*''[[Facivermis]]''<ref name=":27" />
*''[[Fusuconcharium]]''<ref name=":38">{{Cite journal|last1=Zhang|first1=Xi-Guang|last2=Aldridge|first2=Richard J.|date=2007|title=Development and Diversification of Trunk Plates of the Lower Cambrian Lobopodians|journal=Palaeontology|language=en|volume=50|issue=2|pages=401–415|doi=10.1111/j.1475-4983.2006.00634.x|bibcode=2007Palgy..50..401Z |s2cid=85293118 |issn=1475-4983|doi-access=free}}</ref>
*''[[Hadranax]]''<ref>BUDD, G. E., PEEL, J. S. (1998). [https://www.palass.org/publications/palaeontology-journal/archive/41/6/article_pp1201-1213 A new xenusiid lobopod from the Early Cambrian Sirius Passet fauna of North Greenland]. ''Palaeontology'', 41, 6, 1201–1213.</ref>
* ''[[Hallucigenia]]''<ref name=":30" /><ref name=":31" /><ref name=":36" /><ref name=":2" />
*''[[Jianshanopodia]]''<ref name="Liu2006" />
*''[[Kerygmachela]]''?<ref name=":18" /><ref name=":1" /><ref name=":14" />
*''[[Lenisambulatrix]]''<ref name=":13" />
*''[[Luolishania]]''<ref name=":31" /> (=''[[Miraluolishania]]'')<ref name=":4" /><ref name=":27" />
*''[[Megadictyon]]''<ref>Luo, H. L., Hu, S. X. & Chen, L. Z. ''Early Cambrian Chengjiang Fauna from Kunming Region, China''. 129 (Yunnan Science and Technology Press, 1999).</ref><ref name="Liu2007" />
*''[[Microdictyon]]''<ref name=":33" />
*''[[Mobulavermis]]''?<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 |doi=10.1017/jpa.2023.63 |access-date=13 December 2023}}</ref>
*''[[Omnidens]]''?<ref name="Hou2006">{{Cite journal |last1=Hou |first1=Xianguang |last2=Bergström |first2=Jan |last3=Jie |first3=Yang |year=2006 |title=Distinguishing anomalocaridids from arthropods and priapulids |journal=Geological Journal |volume=41 |issue=3–4 |pages=259–269 |bibcode=2006GeolJ..41..259X |doi=10.1002/gj.1050 |s2cid=83582128}}</ref>
*''[[Onychodictyon]]''<ref name=":37" /><ref name=":22" />
*''[[Orstenotubulus]]''<ref>{{Cite journal|last1=Maas|first1=Andreas|last2=Mayer|first2=Georg|last3=Kristensen|first3=Reinhardt M.|last4=Waloszek|first4=Dieter|date=2007-12-01|title=A Cambrian micro-lobopodian and the evolution of arthropod locomotion and reproduction|url=https://doi.org/10.1007/s11434-007-0515-3|journal=Chinese Science Bulletin|language=en|volume=52|issue=24|pages=3385–3392|doi=10.1007/s11434-007-0515-3|bibcode=2007ChSBu..52.3385M|s2cid=83993887|issn=1861-9541}}</ref>
*''[[Ovatiovermis]]''<ref name=":6" />
*''[[Pambdelurion]]''?<ref name=":20" /><ref name=":29" /><ref name=":7" />
*''[[Parvibellus]]''?<ref name="McCall2023"/>
*''[[Paucipodia]]''<ref>{{Cite journal|last1=Jun-yuan|first1=Chen|last2=Gui-qing|first2=Zhou|last3=Ramsköld|first3=Lars|date=1994|title=A new Early Cambrian onychophoran-like animal, ''Paucipodia'' gen. nov., from the Chengjiang fauna, China|url=https://www.cambridge.org/core/journals/earth-and-environmental-science-transactions-of-royal-society-of-edinburgh/article/abs/new-early-cambrian-onychophoranlike-animal-paucipodia-gen-nov-from-the-chengjiang-fauna-china/9B3B37AC45F3F5815C251E0675A3A4A4|journal=Earth and Environmental Science Transactions of the Royal Society of Edinburgh|language=en|volume=85|issue=4|pages=275–282|doi=10.1017/S0263593300002042|s2cid=131555757 |issn=1473-7116}}</ref><ref name="Hou2004" />
*''[[Quadratapora]]''<ref name=":38" />
*''[[Siberion]]''<ref name=":9" />
*''[[Thanahita]]''<ref name=":11" />
*''[[Tritonychus]]''<ref name=":34" />
*''[[Utahnax]]''?<ref>{{cite journal |last1=Lerosey-Aubril |first1=R. |last2=Ortega-Hernández |first2=J. |year=2022 |title=A new lobopodian from the middle Cambrian of Utah: did swimming body flaps convergently evolve in stem-group arthropods? |journal=Papers in Palaeontology |volume=8 |issue=3 |pages=e1450 |doi=10.1002/spp2.1450 |s2cid=250076505}}</ref>
*''[[Xenusion]]''<ref name=":19" />
*''[[Youti]]''?<ref>{{cite journal |last1=Smith |first1=Martin R. |last2=Long |first2=Emma J. |last3=Dhungana |first3=Alavya |last4=Dobson |first4=Katherine J. |last5=Yang |first5=Jie |last6=Zhang |first6=Xiguang |year=2024 |title=Organ systems of a Cambrian euarthropod larva |journal=Nature |volume=624 |issue=8028 |pages=123–128 |doi=10.1038/s41586-024-07756-8|doi-access=free|pmid=39085610 |pmc=11374701 }}</ref>


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== References ==

{{Reflist}}

{{Animalia}}
{{Lobopodia}}
{{Taxonbar|from=Q5189}}

[[Category:Lobopodia| ]]
[[Category:Prehistoric protostomes]]
[[Category:Ecdysozoa phyla|†]]
[[Category:Cambrian Series 2 first appearances]]
[[Category:Paraphyletic groups]]