:en:Lobopodia#Gilled lobopodians

File:20210817 Lobopodia Lobopodian Lobopod definitions.png.]]

The Lobopodian concept varies from author to author. 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).{{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}} Certain Dinocaridid genera, such as Opabinia, Pambdelurion, and Kerygmachela, may also be regarded as lobopodians,{{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}} sometimes referred to more specifically as "gilled lobopodians" or "gilled lobopods".{{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}} This traditional, informal usage of "Lobopodia" treats it as an evolutionary grade, including only extinct Panarthropods near the base of 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.{{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}}{{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|bibcode=2017ArtSD..46..354O }} This corresponds to "A" in the image to the left.

An alternative, broader definition of Lobopodia would also incorporate Onychophora and Tardigrada,{{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|bibcode=1989Letha..22..169D }} the two living panarthropod phyla which still bear lobopodous limbs. This definition, corresponding to "C", is a 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. "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.{{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 |bibcode=2017ArtSD..46..328S |issn=1467-8039}} The broadest definition treats Lobopodia as a monophyletic superphylum equivalent in 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.{{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}}

Lobopodia has, historically, sometimes included Pentastomida, a group of parasitic panarthropod which were traditionally thought to be a unique phylum,[http://sea-entomologia.org/IDE@/revista_98B.pdf Pentastomida - Sociedad Entomológica Aragonesa][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] but revealed by subsequent phylogenomic and anatomical studies to be a highly specialized taxon of crustaceans.{{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}}{{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}}{{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}}{{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}}{{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}}

{{multiple image

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| footer = Aysheaia pedunculata and Hallucigenia sparsa, two of the most iconic as well as the first described lobopodians.

| image1 = Aysheaia2.jpg

| image2 = H. sparsa.jpg

}}

The better-known 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 — 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.{{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}} 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.{{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}}

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. Luolishania is an iconic example of lobopodians with multiple pairs of specialized appendages. The gill lobopodians Kerygmachela and Pambdelurion shed light on the relationship between lobopodians and arthropods, as they have both lobopodian affinities and characteristics linked to the arthropod stem-group.

File:Aysheaia Walcott 1911.png pedunculata, showing overall morphology.]]

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 centimeters.

Most lobopodians were only a few centimeters in length, while some genera grew up to over 20 centimeters. Their bodies are 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. Body and appendages are circular in cross-section.

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| 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. The head of a lobopodian is more or less bulbous, and sometime possesses a pair of pre-ocular, presumely protocerebral appendages – for example, primary antennae{{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|bibcode=2009ArtSD..38..271M }} or well-developed frontal appendages,{{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}} which are individualized from the trunk lobopods{{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}} (with the exception of Antennacanthopodia, which have two pairs of head appendages instead of one). Mouthparts may consist of rows of teeth{{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}} or a conical proboscis.{{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}} The eyes may be represented by a single ocellus or by numerous pairs of simple ocelli, as has been shown in Luolishania (=Miraluolishania{{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|bibcode=2009Letha..42..265S |issn=1502-3931}}), Ovatiovermis, Onychodictyon, Hallucigenia, Facivermis, and less certainly Aysheaia as well. However, in gilled lobopodians like Kerygmachela, the eyes are relatively complex reflective patches{{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}} that may had been compound in nature.{{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}}

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| 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 or lobopodous limbs. 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.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). The trunk segments may bear other external, segment-corresponding structures such as nodes (e.g. Hadranax, Kerygmachela), papillae (e.g. Onychodictyon), spine/plate-like sclerites (e.g. armoured lobopodians) or lateral flaps (e.g. gilled lobopodians). The trunk may terminate with a pair of lobopods (e.g. Aysheaia, Hallucigenia sparsa) or a tail-like extension (e.g. Paucipodia, Siberion, Jianshanopodia).

The lobopods are flexible and loosely conical in shape, tapering from the body to tips that may or may not {{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}}{{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}}{{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}} bear claws. The claws, if present, are hardened structures with a shape resembling a hook or gently-curved spine.{{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}} Claw-bearing lobopods usually have two claws, but single claws are known (e.g. posterior lobopods of luolishaniids), as are more than two (e.g. three in Tritonychus, seven in Aysheaia) depending on its segmental or taxonomical association. In some genera, the lobopods bear additional structures such as spines (e.g. Diania), fleshy outgrowths (e.g. Onychodictyon), or tubercules (e.g. Jianshanopodia). There is no sign of 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{{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}} is considered to be a misinterpretation.

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.

File:Jianshanopodia decora.jpg decora, showing traces of lobopods, gut diverculae and lobe-like terminal extension.]]

The gut of lobopodians is often straight, undifferentiated,{{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}} and sometimes preserved in the fossil record in three dimensions. In some specimens the gut is found to be filled with sediment.{{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|bibcode=2004Letha..37..235H }} The gut consists of a central tube occupying the full length of the lobopodian's trunk,{{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}} 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).{{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}} 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,{{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 |issue=1 |doi=10.1666/0094-8373(2002)028<0155:LGATIO>2.0.CO;2 |bibcode=2002Pbio...28..155B |s2cid=85606166}} because the phosphate content of the guts is under 1%; the contents comprise quartz and muscovite. 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.]]

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. 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.

In some extant ecdysozoan such as priapulids and onychophorans, 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, 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.{{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}}

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.

{{multiple image

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| 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". Function of the sclerites were interpreted as protective armor and/or muscle attachment points. In some cases, only the disarticulated sclerites of the animal were preserved, which represented as component of small shelly fossils (SSF). Armoured lobopodians were suggest to be onychophoran-related and may even represent a clade in some previous studies, but their phylogenetic positions in later studies are controversial. (see text)

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File:20210730 Gilled lobopodians Pambdelurion Kerygmachela.png (top left) and Kerygmachela (bottom right).]]

Dinocaridids with lobopodian affinities (due to shared features like annulation and lobopods) are referred to as "gilled lobopodians" or "gilled lobopods". 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.{{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|bibcode=2023JPal...97.1009M }} Opabinia may also fall under this category in a broader sense,{{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}}{{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}} although the presence of lobopods in this genus is not definitively proven.{{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}} Omnidens, a genus known only from Pambdelurion-like mouthparts and distal parts of the frontal appendages, may also be a gilled lobopodian.{{cite journal |last1=Li |first1=Wei |last2=Yang |first2=Jie |last3=Yang |first3=Xiaoyu |last4=Dhungana |first4=Alavya |last5=Wang |first5=Yu |last6=Zhang |first6=Xiguang |last7=Smith |first7=Martin R. |date=November 2024 |title=Omnidens appendages and the origin of radiodont mouthparts |url=https://onlinelibrary.wiley.com/doi/10.1002/spp2.1600 |journal=Papers in Palaeontology |language=en |volume=10 |issue=6 |doi=10.1002/spp2.1600 |bibcode=2024PPal...10E1600L |issn=2056-2799}} The body flaps may have functioned as both swimming appendages and gills, and are possibly homologous to the dorsal flaps of radiodonts and exites of Euarthropoda. Whether these genera were true lobopodians is still contested by some.{{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}} However, they are widely accepted as stem-group arthropods just basal to radiodonts.

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{{further|Siberiidae}}File:20191217 Siberiida Siberion Megadictyon Jianshanopodia.png (upper left), Megadictyon (bottom center) and Jianshanopodia (upper right).]]

Siberion, Megadictyon and Jianshanopodia may be grouped as siberiids (order Siberiida),{{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://web.archive.org/web/20170808022647/http://paleoitalia.org/media/u/archives/7.Dzik_-_BollSPI_50-1.pdf |archive-date=2017-08-08 |url-status=usurped |journal=Bollettino della Societa Paleontologica Italiana |volume=50 |pages=65–74}} jianshanopodians or "giant lobopodians"{{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}} by some literatures. They are generally large — body length ranging from {{cvt|7|to|22|cm|sigfig=1}} — xenusiid lobopodians with widen trunk, stout trunk lobopods without evidence of claws, and most notably a pair of robust frontal appendages. With the possible exception of Siberion, they also have digestive glands like those of a gilled lobopodian and basal euarthropod. Their anatomy represent transitional forms between typical xenusiids and gilled lobopodians, eventually placing them under the basalmost position of arthropod stem-group.

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{{multiple image

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| image1 = Ovatiovermis cribratus life restoration.jpg

| caption1 = Reconstruction of a 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.

| image2 = Pambdelurion whittingtoni.JPG

| caption2 = Reconstruction of the gilled lobopodian Pambdelurion whittingtoni as a nektonic predator.

}}

Lobopodians possibly occupied a wide range of ecological niches. Although most of them had undifferentiated appendages and straight gut, which would suggest a simple sediment-feeding lifestyle, sophisticated digestive glands and large size of gilled lobopodians and siberiids would allow them to consume larger food items, and their robust frontal appendages may even suggest a predatory lifestyle. On the other hand, luolishaniids such as Luolishania and Ovatiovermis have elaborate feather-like lobopods that presumably formed 'baskets' for suspension or filter-feeding.{{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}} Lobopods with curved terminal claws may have given some lobopodians the ability to climb on harder substrates like rocks, sponges, or animal carcasses.

Not much is known about the physiology of lobopodians. There is evidence to suggest that lobopodians moult just like other ecdysozoan taxa, but the outline and ornamentation of the harden sclerite did not vary during ontogeny. The gill-like structures on the body flaps of gilled lobopodians and ramified extensions on the lobopods of Jianshanopodia may provide respiratory function (gills). Pambdelurion may control the movement of their lobopods in a way similar to onychophorans.{{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}}

During the Cambrian, lobopodians displayed a substantial degree of biodiversity. One species is known from each of the Ordovician and Silurian periods,{{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}} with a few more known from the Carboniferous (Mazon Creek) — this represents the paucity of exceptional lagerstatten in post-Cambrian deposits.

{{original research section|date=December 2024}}

{{cladogram

|title=

|align= right

|caption=Neutralized phylogeny between lobopodians and other Ecdysozoan taxa.{{excessive citations inline|date=December 2024}} 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=Ecdysozoa|1={{clade

|label1=Cycloneuralia|1=Priapulida 50px, Nematoda 70px and relatives

|label2=Panarthropoda|2={{clade

|1={{clade

|1=(Lobopodian taxa controversial)

|2={{clade

|1=Antennacanthopodia 80px

|2=Crown-group Onychophora 80px

}} }}

|2={{clade

|1=(Lobopodian taxa controversial)

|2=Crown-group Tardigrada 60px

}}

|3=(Lobopodian taxa controversial)

|4={{clade

|1=Megadictyon 80px and Jianshanopodia 80px

|2={{clade

|1=Pambdelurion 80px and Kerygmachela 80px

|2={{clade

|1=Opabinia 80px

|2=Radiodonta 70px

|3=Euarthropoda 70 px 80 px 70 px

}} }} }} }} }} }} }}

The overall phylogenetic interpretation on lobopodians has changed dramatically since their discovery and first description. The reassignments are not only based on new fossil evidence, but also new embryological, neuroanatomical, and genomic (e.g. gene expression, phylogenomics) information observed from extant panarthropod taxa.{{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}}

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.{{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 |jstor=1304837}}{{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 |volume=351|issue=6323|pages=225–228 |doi=10.1038/351225a0|issn=1476-4687|bibcode=1991Natur.351..225R|s2cid=4309565}}{{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|bibcode=2001ZooAn.240..237B }} This interpretation was challenged after the discovery of lobopodians with arthropod and tardigrade-like characteristics,{{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|bibcode=2001ZooAn.240..265B |issn=0044-5231}} suggesting that the similarity between lobopodians and onychophorans represents deeper panarthropod ancestral traits (plesiomorphies) instead of onychophoran-exclusive characteristics (synapomorphies). 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 dinocaridids, would lead to an arthropod body plan.{{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}} Aysheaia's surface ornamentation, if homologous with palaeoscolecid sclerites, may represent a deeper link connecting it with cycloneuralian outgroups. Lobopodians are paraphyletic, and include the last common ancestor of arthropods, onychophorans and tardigrades.

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).{{excessive citations inline|date=December 2024}} 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). 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. On the other hand, primary antennae and frontal appendages of lobopodians and dinocaridids may be homologous to the labrum/hypostome complex of euarthropods, an idea support by their protocerebral origin and developmental pattern of the labrum of extant arthropods.

File:20191201 Radiodonta Amplectobelua Anomalocaris Aegirocassis Lyrarapax Peytoia Laggania Hurdia.png|Radiodonts are stem-group arthropods with gilled lobopodian-like body flaps, arthropodized frontal appendages and stalked compound eyes.

File:20191112 Pambdelurion whittingtoni.png|Restoration of Pambdelurion a "gilled lobopodian" related to arthropods, which has both pairs of lobopods and lateral flaps.

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. However, this interpretation is questionable as the data provided by the original description are not consistent with the suspected phylogenic relationships.{{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 |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}}{{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}} 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'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. 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.

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

While Antennacanthopodia is widely accepted as a stem-group onychophoran, 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 or basal panarthropods,{{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}} with a few species (Aysheaia{{excessive citations inline|date=December 2024}} or Onychodictyon ferox) 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. This interpretation was questioned by later studies, as the structures may be a panarthropod plesiomorphy.

File:OrstenTardigrade.jpg” tardigrade, a parasitic stem-lineage tardigrade, known from fossils recovered from the Cambrian Kuonamka Formation of Siberia.{{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 |bibcode=2001ZooAn.240..451M |issn=0044-5231}}]]

Lobopodian taxa of the tardigrade stem-group is unclear. Aysheaia or Onychodictyon ferox 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). Although not widely accepted, there are even suggestions that Tardigrada itself representing the basalmost panarthropod or branch between the arthropod stem-group. However, a paper in 2023 found luolishaniids to be the closest relatives of tardigrades using various morphological characteristics. {{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|bibcode=2023PNAS..12011251K }}

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; while other studies rather suggest luolishaniid and hallucigenid, two lobopodian taxa which had been resolved as members of stem-group onychophorans as well.

File:Aysheaia pedunculata.jpg pedunculata.]]

File:Microdictyon Chengjiang.JPG sinicum.]]

File:Mureropodia apae - Xenusia - Lower Cambrian - Murero, Spain.jpg cf. camurus.]]

File:Facivermis 2.png, an unusual lobopodian with limbless posterior region that lived like a tube worm]]

As of 2018, over 20 lobopodian genera have been described. The fossil materials being described as lobopodians Mureropodia apae and Aysheaia prolata are considered to be disarticulated frontal appendages of the radiodonts Caryosyntrips and Stanleycaris, respectively.{{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|bibcode=2017PPal....3..461P |s2cid=135026011 |issn=2056-2802|url=http://osf.io/5avkg/}}{{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}}{{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}} Miraluolishania was suggested to be synonym of Luolishania by some studies.{{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}} The enigmatic Facivermis was later revealed to be a highly specialized genus of luolishaniid lobopodians.{{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|bibcode=2020CBio...30E1529H }}

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• Acinocricus{{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}}
• Antennacanthopodia
• Aysheaia
• Carbotubulus
• Cardiodictyon{{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}}
• Collinsium{{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}}
• Collinsovermis{{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|bibcode=2020Palgy..63..979C |s2cid=225593728|issn=1475-4983}}
• Diania
• Entothyreos{{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}}
• Facivermis
• Fusuconcharium{{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}}
• HadranaxBUDD, 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.
• Hallucigenia
• Jianshanopodia
• Kerygmachela?
• Lenisambulatrix
• Luolishania (=Miraluolishania)
• MegadictyonLuo, H. L., Hu, S. X. & Chen, L. Z. Early Cambrian Chengjiang Fauna from Kunming Region, China. 129 (Yunnan Science and Technology Press, 1999).
• Microdictyon
• Mobulavermis?{{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 |bibcode=2023JPal...97.1009M |access-date=13 December 2023}}
• Omnidens?{{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}}
• Onychodictyon
• Orstenotubulus{{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}}
• Ovatiovermis
• Pambdelurion?
• Parvibellus?
• Paucipodia{{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}}
• Quadratapora
• Siberion
• Thanahita
• Tritonychus
• Utahnax?{{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 |bibcode=2022PPal....8E1450L |s2cid=250076505}}
• Xenusion
• Youti?{{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 |bibcode=2024Natur.633..120S }}

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{{Reflist}}

{{Animalia}}

{{Lobopodia}}

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Category:Prehistoric protostomes

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Category:Cambrian Series 2 first appearances

Category:Paraphyletic groups