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Lobopodia

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Lobopodia
Temporal range: Cambrian Series 2–Early Pennsylvanian[1] Descendant taxa Onychophora, Tardigrada, and Euarthropoda survive to Recent, possible Ediacaran ichnofossils [2]
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
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
Scientific classificationEdit this classification
Domain: Eukaryota
Kingdom: Animalia
Subkingdom: Eumetazoa
Clade: ParaHoxozoa
Clade: Bilateria
Clade: Nephrozoa
(unranked): Protostomia
Superphylum: Ecdysozoa
(unranked): Panarthropoda
Phylum: "Lobopodia"
Snodgrass 1938
Groups included
Cladistically included but traditionally excluded taxa

Crown-group Euarthropoda

Synonyms

Lobopodians are members of the informal group Lobopodia[3] (from the Greek, meaning "blunt feet"), or the formally erected phylum Lobopoda Cavalier-Smith (1998).[4] They are panarthropods with stubby legs called lobopods,[5] a term which may also be used as a common name of this group as well.[6][7] While the definition of lobopodians may differ between literatures,[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”. [9][5][10]

The oldest near-complete fossil lobopodians date to the Lower Cambrian; some are also known from Ordovician, Silurian and Carboniferous Lagerstätten.[11][12][13] Some bear toughened claws, plates or spines, which are commonly preserved as carbonaceous or mineralized microfossils in Cambrian strata.[14][15] 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

[edit]
Various definitions of lobopodians within Panarthropoda.[8]

The Lobopodian concept varies from author to author.[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).[16][17][18] Certain Dinocaridid genera, such as Opabinia, Pambdelurion, and Kerygmachela, may also be regarded as lobopodians,[19][10] sometimes referred to more specifically as "gilled lobopodians" or "gilled lobopods".[20] 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.[5][21][22][8][23][24] This corresponds to "A" in the image to the left.

An alternative, broader definition of Lobopodia would also incorporate Onychophora and Tardigrada,[16][19][4] 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.[5] "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.[25] 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.[26][6]

Lobopodia has, historically, sometimes included Pentastomida,[27] a group of parasitic panarthropod which were traditionally thought to be a unique phylum,[28][29] but revealed by subsequent phylogenomic and anatomical studies to be a highly specialized taxon of crustaceans.[30][31][32][33][34]

Representative taxa

[edit]
Aysheaia pedunculata and Hallucigenia sparsa, two of the most iconic as well as the first described[5] lobopodians.

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[21] — 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.[35] 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.[14][22]

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.[16][10] Luolishania is an iconic example of lobopodians with multiple pairs of specialized appendages.[36] 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.[20][26]

Morphology

[edit]
Complete fossil of Aysheaia pedunculata, showing overall morphology.

Most lobopodians were only a few centimeters in length, while some genera grew up to over 20 centimeters.[7] 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.[37] Body and appendages are circular in cross-section.[37]

[edit]
Anterior section of Onychodictyon ferox, showing head structures.
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.[38][22] The head of a lobopodian is more or less bulbous,[5] and sometime possesses a pair of pre-ocular, presumely protocerebral[23] appendages – for example, primary antennae[39][36][23][40] or well-developed frontal appendages,[41][19][42][7][5] which are individualized from the trunk lobopods[23][43] (with the exception of Antennacanthopodia, which have two pairs of head appendages instead of one[39]). Mouthparts may consist of rows of teeth[37][22][42][7][44] or a conical proboscis.[38][5][45] The eyes may be represented by a single ocellus or by numerous[46] pairs of simple ocelli,[5] as has been shown in Luolishania[36] (=Miraluolishania[46][47]), Ovatiovermis,[45] Onychodictyon,[38] Hallucigenia,[22] Facivermis,[47] and less certainly Aysheaia as well.[38] However, in gilled lobopodians like Kerygmachela, the eyes are relatively complex reflective patches[48] that may had been compound in nature.[49]

Trunk and lobopods

[edit]
Paucipodia inermis, a lobopodian with featureless, undifferentiated trunk region.
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[5] or lobopodous limbs.[19] 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.[50][36][21] The trunk segments may bear other external, segment-corresponding structures such as nodes (e.g. Hadranax,[6] Kerygmachela[19]), papillae (e.g. Onychodictyon[38]), spine/plate-like sclerites (e.g. armoured lobopodians[5]) or lateral flaps (e.g. gilled lobopodians[19][44]). The trunk may terminate with a pair of lobopods (e.g. Aysheaia, Hallucigenia sparsa)[22] or a tail-like extension (e.g. Paucipodia, Siberion, Jianshanopodia).[50][37][7][27]

The lobopods are flexible and loosely conical in shape, tapering from the body to tips that may [21][5] or may not [39][51][10] bear claws. The claws, if present, are hardened structures with a shape resembling a hook or gently-curved spine.[37][52][36][21][5] Claw-bearing lobopods usually have two claws, but single claws are known (e.g. posterior lobopods of luolishaniids[36][45][40]), as are more than two (e.g. three in Tritonychus,[53] seven in Aysheaia[41]) depending on its segmental or taxonomical association.[21] In some genera, the lobopods bear additional structures such as spines (e.g. Diania[51]), fleshy outgrowths (e.g. Onychodictyon[38]), or tubercules (e.g. Jianshanopodia[7]). 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[54] is considered to be a misinterpretation.[51][10]

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.[5][22][45][24][40]

Internal structures

[edit]
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,[55] and sometimes preserved in the fossil record in three dimensions. In some specimens the gut is found to be filled with sediment.[37] The gut consists of a central tube occupying the full length of the lobopodian's trunk,[7] 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).[7][42][55] 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,[56] because the phosphate content of the guts is under 1%; the contents comprise quartz and muscovite.[37] 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.

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.[42][37][39] 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.[49]

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,[57] 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.[53]

Categories

[edit]

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.[21][8][23]

Armoured lobopodians

[edit]
Fossil of Microdictyon sinicum, showing pairs of sclerite and trace of trunk and lobopods.
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".[39][10] Function of the sclerites were interpreted as protective armor and/or muscle attachment points.[50][58][5] In some cases, only the disarticulated sclerites of the animal were preserved, which represented as component of small shelly fossils (SSF).[50][14] Armoured lobopodians were suggest to be onychophoran-related and may even represent a clade in some previous studies,[58] but their phylogenetic positions in later studies are controversial. (see text)

Gilled lobopodians

[edit]
The gilled lobopodians Pambdelurion (top left) and Kerygmachela (bottom right).

Dinocaridids with lobopodian affinities (due to shared features like annulation and lobopods) are referred to as "gilled lobopodians"[8][44][57] or "gilled lobopods".[20] 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.[10][59] Opabinia may also fall under this category in a broader sense,[8][60] although the presence of lobopods in this genus is not definitively proven.[61] Omnidens, a genus known only from a Pambdelurion-like mouth apparatus, may also be a gilled lobopodian.[44] The body flaps may have functioned as both swimming appendages and gills,[20] and are possibly homologous to the dorsal flaps of radiodonts and exites of Euarthropoda.[19][60] Whether these genera were true lobopodians is still contested by some.[62] However, they are widely accepted as stem-group arthropods just basal to radiodonts.[8][21][22][23]

Siberion and similar taxa

[edit]
The siberiid lobopodians Siberion (upper left), Megadictyon (bottom center) and Jianshanopodia (upper right).

Siberion, Megadictyon and Jianshanopodia may be grouped as siberiids (order Siberiida),[27] jianshanopodians[21] or "giant lobopodians"[63] by some literatures. They are generally large — body length ranging between 7[27] and 22 centimeters[42] (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.[8] With the possible exception of Siberion,[27][21] they also have digestive glands like those of a gilled lobopodian and basal euarthropod.[7][42][8][55] Their anatomy represent transitional forms between typical xenusiids and gilled lobopodians,[27] eventually placing them under the basalmost position of arthropod stem-group.[7][42][8][23]

Paleoecology

[edit]
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.[45]
Reconstruction of the gilled lobopodian Pambdelurion whittingtoni as a nektonic predator.

Lobopodians possibly occupied a wide range of ecological niches.[5] Although most of them had undifferentiated appendages and straight gut, which would suggest a simple sediment-feeding lifestyle,[5] sophisticated digestive glands and large size of gilled lobopodians and siberiids would allow them to consume larger food items,[5][55] and their robust frontal appendages may even suggest a predatory lifestyle.[7][55] On the other hand, luolishaniids such as Luolishania and Ovatiovermis have elaborate feather-like lobopods that presumably formed 'baskets' for suspension or filter-feeding.[36][45] Lobopods with curved terminal claws may have given some lobopodians the ability to climb on substrances.[5]

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.[50][15] The gill-like structures on the body flaps of gilled lobopodians and ramified extensions on the lobopods of Jianshanopodia may provide respiratory function (gills).[20][7] Pambdelurion may control the movement of their lobopods in a way similar to onychophorans.[57]

Distribution

[edit]

During the Cambrian, lobopodians displayed a substantial degree of biodiversity. One species is known from each of the Ordovician and Silurian periods,[12][64] with a few more known from the Carboniferous (Mazon Creek) — this represents the paucity of exceptional lagerstatten in post-Cambrian deposits.

Phylogeny

[edit]
Ecdysozoa
Cycloneuralia

Priapulida , Nematoda and relatives

Panarthropoda

(Lobopodian taxa controversial)

(Lobopodian taxa controversial)

Crown-group Tardigrada

(Lobopodian taxa controversial)

Neutralized phylogeny between lobopodians and other Ecdysozoan taxa.[21][8][22][60][23][45][24] Extant panarthropod taxa are in bold. Relationship between the total-group of extant panarthropod phyla is unresolved.

The overall phylogenetic interpretation on lobopodians has changed dramatically since their discovery and first description.[5] 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.[5][23][65]

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.[66][17][18][67][5] This interpretation was challenged after the discovery of lobopodians with arthropod and tardigrade-like characteristics,[68] suggesting that the similarity between lobopodians and onychophorans represents deeper panarthropod ancestral traits (plesiomorphies) instead of onychophoran-exclusive characteristics (synapomorphies).[24] 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.[58] Aysheaia's surface ornamentation, if homologous with palaeoscolecid sclerites, may represent a deeper link connecting it with cycloneuralian outgroups.[58] Many further studies followed and extended the idea, generally in agreement that all three panarthropod phyla have lobopodians in their stem lineages.[5][21][22][23][45][24] Lobopodians are thus paraphyletic, and include the last common ancestor of arthropods, onychophorans and tardigrades.[5]

Stem-group arthropods

[edit]

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).[21][8][22][60][23][45][24] 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).[8][23] 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.[43] 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[8][23][49] and developmental pattern of the labrum of extant arthropods.[43][23]

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.[54] However, this interpretation is questionable as the data provided by the original description are not consistent with the suspected phylogenic relationships.[69][70] 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.[51][10] 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.[51][10]

Stem-group onychophorans

[edit]
Antennacanthopodia gracilis, a lobopodian suggested to be a stem-group onychophoran.

While Antennacanthopodia is widely accepted as a stem-group onychophoran,[21][22][53][45][24][47] 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[21][22][53][47] or basal panarthropods,[45][24][40] with a few species (Aysheaia[45][24][40] or Onychodictyon ferox[21][22]) 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.[21] This interpretation was questioned by later studies, as the structures may be a panarthropod plesiomorphy.[24][40]

Stem-group tardigrades

[edit]
Artistic reconstruction of the “Orsten” tardigrade, a parasitic stem-lineage tardigrade, known from fossils recovered from the Cambrian Kuonamka Formation of Siberia.[71]

Lobopodian taxa of the tardigrade stem-group is unclear.[5] Aysheaia[45][24][40] or Onychodictyon ferox[21][22] 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).[21] Although not widely accepted, there are even suggestions that Tardigrada itself representing the basalmost panarthropod or branch between the arthropod stem-group.[68] However, a paper in 2023 found luolishaniids to be the closest relatives of tardigrades using various morphological characteristics. [72]

Stem-group panarthropods

[edit]

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;[58][21][22][47] while other studies rather suggest luolishaniid and hallucigenid,[45][24][40] two lobopodian taxa which had been resolved as members of stem-group onychophorans as well.[5][21][22][53][47]

Described genera

[edit]
Fossil of Aysheaia pedunculata.
Fossil of Microdictyon sinicum.
Fossil of "Mureropodia apae", which may be in fact frontal appendage of Caryosyntrips cf. camurus.
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.[10] 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.[73][74][75] Miraluolishania was suggested to be synonym of Luolishania by some studies.[36][76][47] The enigmatic Facivermis was later revealed to be a highly specialized genus of luolishaniid lobopodians.[27][45][47]

References

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  1. ^ Haug, J.T.; Mayer, G.; Haug, C.; Briggs, D.E.G. (2012). "A Carboniferous non-Onychophoran Lobopodian reveals long-term survival of a Cambrian morphotype". Current Biology. 22 (18): 1673–1675. doi:10.1016/j.cub.2012.06.066. PMID 22885062.
  2. ^ Chen, Zhe; Chen, Xiang; Zhou, Chuanming; Yuan, Xunlai; Xiao, Shuhai (6 June 2018). "Late Ediacaran trackways produced by bilaterian animals with paired appendages". Science Advances. 4 (6). doi:10.1126/sciadv.aao6691. hdl:10919/84444.
  3. ^ Snodgrass, R.E. (1938). "Evolution of the Annelida, Onychophora, and Arthropoda". Smithsonian Miscellaneous Collections. 97 (6): 1–159.
  4. ^ a b Cavalier-Smith, T. (1998). "A revised six-kingdom system of life". Biological Reviews. 73 (3): 203–266. doi:10.1017/S0006323198005167 (inactive 2024-04-26). PMID 9809012.{{cite journal}}: CS1 maint: DOI inactive as of April 2024 (link)
  5. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa Ortega-Hernández, Javier (2015-10-05). "Lobopodians". Current Biology. 25 (19): R873–R875. doi:10.1016/j.cub.2015.07.028. ISSN 0960-9822. PMID 26439350. Cite error: The named reference ":0" was defined multiple times with different content (see the help page).
  6. ^ a b c Budd, Graham; Peel, John (1998-12-01). "A new Xenusiid lobopod from the early Cambrian Sirius Passet fauna of North Greenland". Palaeontology. 41: 1201–1213.
  7. ^ a b c d e f g h i j k l m Jianni Liu; Degan Shu; Jian Han; Zhifei Zhang & Xingliang Zhang (2006). "A large xenusiid lobopod with complex appendages from the Lower Cambrian Chengjiang Lagerstätte" (PDF). Acta Palaeontol. Pol. 51 (2): 215–222. Archived (PDF) from the original on 2022-10-10. Retrieved 9 February 2011.
  8. ^ a b c d e f g h i j k l m n o Ortega-Hernández, Javier (December 2014). "Making sense of 'lower' and 'upper' stem-group Euarthropoda, with comments on the strict use of the name Arthropoda von Siebold, 1848". Biological Reviews of the Cambridge Philosophical Society. 91 (1): 255–273. doi:10.1111/brv.12168. ISSN 1469-185X. PMID 25528950. S2CID 7751936.
  9. ^ Liu, Jianni; Dunlop, Jason A. (2014-03-15). "Cambrian lobopodians: A review of recent progress in our understanding of their morphology and evolution". Palaeogeography, Palaeoclimatology, Palaeoecology. 398: 4–15. Bibcode:2014PPP...398....4L. doi:10.1016/j.palaeo.2013.06.008. ISSN 0031-0182.
  10. ^ a b c d e f g h i j k Ou, Qiang; Mayer, Georg (2018-12-01). "A Cambrian unarmoured lobopodian, †Lenisambulatrix humboldti gen. et sp. nov., compared with new material of †Diania cactiformis". Scientific Reports. 8 (1): 13667. Bibcode:2018NatSR...813667O. doi:10.1038/s41598-018-31499-y. PMC 6147921. PMID 30237414.
  11. ^ van Roy, P.; Orr, P.J.; Botting, J.P.; Muir, L.A.; Vinther, J.; Lefebvre, B.; Hariri, K.E.; Briggs, D.E.G. (2010). "Ordovician faunas of Burgess Shale type". Nature. 465 (7295): 215–218. Bibcode:2010Natur.465..215V. doi:10.1038/nature09038. PMID 20463737. S2CID 4313285.
  12. ^ a b von Bitter, P.H.; Purnell, M.A.; Tetreault, D.K.; Stott, C.A. (2007). "Eramosa Lagerstätte—Exceptionally preserved soft-bodied biotas with shallow-marine shelly and bioturbating organisms (Silurian, Ontario, Canada)". Geology. 35 (10): 879. Bibcode:2007Geo....35..879V. doi:10.1130/G23894A.1. S2CID 11561169.
  13. ^ a b Haug, J.T.; Mayer, G.; Haug, C.; Briggs, D.E.G. (2012). "A Carboniferous non-Onychophoran Lobopodian reveals long-term survival of a Cambrian morphotype". Current Biology. 22 (18): 1673–1675. doi:10.1016/j.cub.2012.06.066. PMID 22885062.
  14. ^ a b c Caron, J.-B.; Smith, M.R.; Harvey, T.H.P. (2013). "Beyond the Burgess Shale: Cambrian microfossils track the rise and fall of hallucigeniid lobopodians". Proceedings of the Royal Society B: Biological Sciences. 280 (1767): 20131613. doi:10.1098/rspb.2013.1613. PMC 3735267. PMID 23902914.
  15. ^ a b Topper, T.P.; Skovsted, C.B.; Peel, J.S.; Harper, D.A.T. (2013). "Moulting in the lobopodian Onychodictyon from the lower Cambrian of Greenland". Lethaia. 46 (4): 490–495. doi:10.1111/let.12026.
  16. ^ a b c d Dzik, Jerzy; Krumbiegel, Günter (1989). "The oldest 'onychophoran' Xenusion: a link connecting phyla?". Lethaia. 22 (2): 169–181. doi:10.1111/j.1502-3931.1989.tb01679.x. ISSN 1502-3931.
  17. ^ a b c Ramsköld, L.; Xianguang, Hou (1991). "New early Cambrian animal and onychophoran affinities of enigmatic metazoans". Nature. 351 (6323): 225–228. Bibcode:1991Natur.351..225R. doi:10.1038/351225a0. ISSN 1476-4687. S2CID 4309565.
  18. ^ a b c d HOU, XIANGUANG; BERGSTRÖM, JAN (1995-05-01). "Cambrian lobopodians-ancestors of extant onychophorans?". Zoological Journal of the Linnean Society. 114 (1): 3–19. doi:10.1111/j.1096-3642.1995.tb00110.x. ISSN 0024-4082.
  19. ^ a b c d e f g h Budd, Graham E. (1998). "The morphology and phylogenetic significance of Kerygmachela kierkegaardi Budd (Buen Formation, Lower Cambrian, N Greenland)". Earth and Environmental Science Transactions of the Royal Society of Edinburgh. 89 (4): 249–290. doi:10.1017/S0263593300002418. ISSN 1473-7116. S2CID 85645934.
  20. ^ a b c d e f Budd, Graham (August 1993). "A Cambrian gilled lobopod from Greenland". Nature. 364 (6439): 709–711. Bibcode:1993Natur.364..709B. doi:10.1038/364709a0. ISSN 1476-4687. S2CID 4341971.
  21. ^ a b c d e f g h i j k l m n o p q r s t u Smith, Martin R.; Ortega-Hernández, Javier (2014). "Hallucigenia's onychophoran-like claws and the case for Tactopoda" (PDF). Nature. 514 (7522): 363–366. Bibcode:2014Natur.514..363S. doi:10.1038/nature13576. PMID 25132546. S2CID 205239797. Archived (PDF) from the original on 2022-10-10.
  22. ^ a b c d e f g h i j k l m n o p q r Smith, Martin R.; Caron, Jean-Bernard (July 2015). "Hallucigenia's head and the pharyngeal armature of early ecdysozoans". Nature. 523 (7558): 75–78. Bibcode:2015Natur.523...75S. doi:10.1038/nature14573. ISSN 0028-0836. PMID 26106857. S2CID 205244325.
  23. ^ a b c d e f g h i j k l m n Ortega-Hernández, Javier; Janssen, Ralf; Budd, Graham E. (2017-05-01). "Origin and evolution of the panarthropod head – A palaeobiological and developmental perspective". Arthropod Structure & Development. Evolution of Segmentation. 46 (3): 354–379. doi:10.1016/j.asd.2016.10.011. ISSN 1467-8039. PMID 27989966.
  24. ^ a b c d e f g h i j k l m Siveter, Derek J.; Briggs, Derek E. G.; Siveter, David J.; Sutton, Mark D.; Legg, David (2018). "A three-dimensionally preserved lobopodian from the Herefordshire (Silurian) Lagerstätte, UK". Royal Society Open Science. 5 (8): 172101. doi:10.1098/rsos.172101. PMC 6124121. PMID 30224988.
  25. ^ Smith, Frank W.; Goldstein, Bob (2017-05-01). "Segmentation in Tardigrada and diversification of segmental patterns in Panarthropoda". Arthropod Structure & Development. Evolution of Segmentation. 46 (3): 328–340. doi:10.1016/j.asd.2016.10.005. ISSN 1467-8039. PMID 27725256.
  26. ^ a b c Fortey, Richard A.; Thomas, Richard H. (1997-12-31). Arthropod Relationships. Springer Science & Business Media. ISBN 978-0-412-75420-3.
  27. ^ a b c d e f g h Dzik, Jerzy (1 July 2011). "The xenusian-to-anomalocaridid transition within the lobopodians" (PDF). Bollettino della Societa Paleontologica Italiana. 50: 65–74. Archived (PDF) from the original on 10 October 2022.
  28. ^ Pentastomida - Sociedad Entomológica Aragonesa
  29. ^ Treatise on Zoology - Anatomy, Taxonomy, Biology. The Crustacea, Volum 5
  30. ^ Riley, J.; Banaja, A. A.; James, J. L. (1978-08-01). "The phylogenetic relationships of the pentastomida: The case for their inclusion within the crustacea". International Journal for Parasitology. 8 (4): 245–254. doi:10.1016/0020-7519(78)90087-5. ISSN 0020-7519.
  31. ^ Lavrov, Dennis V.; Brown, Wesley M.; Boore, Jeffrey L. (2004-03-07). "Phylogenetic position of the Pentastomida and (pan)crustacean relationships". Proceedings of the Royal Society of London. Series B: Biological Sciences. 271 (1538): 537–544. doi:10.1098/rspb.2003.2631. PMC 1691615. PMID 15129965.
  32. ^ Regier, Jerome C.; Shultz, Jeffrey W.; Zwick, Andreas; Hussey, April; Ball, Bernard; Wetzer, Regina; Martin, Joel W.; Cunningham, Clifford W. (2010). "Arthropod relationships revealed by phylogenomic analysis of nuclear protein-coding sequences". Nature. 463 (7284): 1079–1083. Bibcode:2010Natur.463.1079R. doi:10.1038/nature08742. ISSN 1476-4687. PMID 20147900. S2CID 4427443.
  33. ^ Lozano-Fernandez, Jesus; Giacomelli, Mattia; Fleming, James F; Chen, Albert; Vinther, Jakob; Thomsen, Philip Francis; Glenner, Henrik; Palero, Ferran; Legg, David A; Iliffe, Thomas M; Pisani, Davide (2019-08-01). "Pancrustacean Evolution Illuminated by Taxon-Rich Genomic-Scale Data Sets with an Expanded Remipede Sampling". Genome Biology and Evolution. 11 (8): 2055–2070. doi:10.1093/gbe/evz097. ISSN 1759-6653. PMC 6684935. PMID 31270537.
  34. ^ Rabet, Nicolas (2021), "Crustaceans", Handbook of Marine Model Organisms in Experimental Biology, CRC Press, pp. 271–287, doi:10.1201/9781003217503-15, ISBN 978-1-003-21750-3, S2CID 239958264
  35. ^ Gould, S.J. (1989). Wonderful Life: The Burgess Shale and the Nature of History. W.W. Norton & Company. Bibcode:1989wlbs.book.....G.[page needed]
  36. ^ a b c d e f g h i Ma, Xiaoya; Hou, Xianguang; Bergström, Jan (2009). "Morphology of Luolishania longicruris (Lower Cambrian, Chengjiang Lagerstätte, SW China) and the phylogenetic relationships within lobopodians". Arthropod Structure & Development. 38 (4): 271–291. doi:10.1016/j.asd.2009.03.001. ISSN 1467-8039. PMID 19293001.
  37. ^ a b c d e f g h i Hou, Xian-Guang; Ma, Xiao-Ya; Zhao, Jie; Bergström, Jan (2004). "The lobopodian Paucipodia inermis from the Lower Cambrian Chengjiang fauna, Yunnan, China". Lethaia. 37 (3): 235–244. doi:10.1080/00241160410006555.
  38. ^ a b c d e f g Ou, Qiang; Shu, Degan; Mayer, Georg (2012-12-11). "Cambrian lobopodians and extant onychophorans provide new insights into early cephalization in Panarthropoda". Nature Communications. 3 (1): 1261. Bibcode:2012NatCo...3.1261O. doi:10.1038/ncomms2272. ISSN 2041-1723. PMC 3535342. PMID 23232391.
  39. ^ a b c d e f Ou, Qiang; Liu, Jianni; SHU, DEGAN; Han, Jian; Zhang, Zhifei; Wan, Xiaoqiao; Lei, Qianping (2011-05-01). "A Rare Onychophoran-Like Lobopodian from the Lower Cambrian Chengjiang Lagerstätte, Southwestern China, and its Phylogenetic Implications". Journal of Paleontology. 85 (3): 587–594. Bibcode:2011JPal...85..587O. doi:10.1666/09-147R2.1. JSTOR 23020193. S2CID 53056128.
  40. ^ a b c d e f g h i Caron, Jean-Bernard; Aria, Cédric (2020). "The Collins' monster, a spinous suspension-feeding lobopodian from the Cambrian Burgess Shale of British Columbia". Palaeontology. 63 (6): 979–994. doi:10.1111/pala.12499. ISSN 1475-4983. S2CID 225593728.
  41. ^ a b c Whittington, Harry Blackmore (1978-11-16). "The Lobopod Animal Aysheaia Pedunculata Walcott, Middle Cambrian, Burgess Shale, British Columbia". Philosophical Transactions of the Royal Society of London. B, Biological Sciences. 284 (1000): 165–197. Bibcode:1978RSPTB.284..165W. doi:10.1098/rstb.1978.0061.
  42. ^ a b c d e f g h Liu, J.; Shu, D.; Han, J.; Zhang, Z.; Zhang, X. (2007). "Morpho-anatomy of the lobopod Magadictyon cf. Haikouensis from the Early Cambrian Chengjiang Lagerstätte, South China". Acta Zoologica. 88 (4): 279–288. doi:10.1111/j.1463-6395.2007.00281.x.
  43. ^ a b c Jockusch, Elizabeth L. (2017-09-01). "Developmental and Evolutionary Perspectives on the Origin and Diversification of Arthropod Appendages". Integrative and Comparative Biology. 57 (3): 533–545. doi:10.1093/icb/icx063. ISSN 1540-7063. PMID 28957524.
  44. ^ a b c d e Vinther, Jakob; Porras, Luis; Young, Fletcher; Budd, Graham; Edgecombe, Gregory (2016-09-01). "The mouth apparatus of the Cambrian gilled lobopodian Pambdelurion whittingtoni". Palaeontology. 59 (6): 841–849. Bibcode:2016Palgy..59..841V. doi:10.1111/pala.12256. hdl:1983/16da11f1-5231-4d6c-9968-69ddc5633a8a. S2CID 88758267.
  45. ^ a b c d e f g h i j k l m n o p Caron, Jean-Bernard; Aria, Cédric (2017-01-31). "Cambrian suspension-feeding lobopodians and the early radiation of panarthropods". BMC Evolutionary Biology. 17 (1): 29. Bibcode:2017BMCEE..17...29C. doi:10.1186/s12862-016-0858-y. ISSN 1471-2148. PMC 5282736. PMID 28137244.
  46. ^ a b Schoenemann, Brigitte; Liu, Jian-Ni; Shu, De-Gan; Han, Jian; Zhang, Zhi-Fei (2009). "A miniscule optimized visual system in the Lower Cambrian". Lethaia. 42 (3): 265–273. doi:10.1111/j.1502-3931.2008.00138.x. ISSN 1502-3931.
  47. ^ a b c d e f g h i j Howard, Richard J.; Hou, Xianguang; Edgecombe, Gregory D.; Salge, Tobias; Shi, Xiaomei; Ma, Xiaoya (2020-02-27). "A Tube-Dwelling Early Cambrian Lobopodian". Current Biology. 30 (8): 1529–1536.e2. doi:10.1016/j.cub.2020.01.075. ISSN 0960-9822. PMID 32109391.
  48. ^ Fleming, James F.; Kristensen, Reinhardt Møbjerg; Sørensen, Martin Vinther; Park, Tae-Yoon S.; Arakawa, Kazuharu; Blaxter, Mark; Rebecchi, Lorena; Guidetti, Roberto; Williams, Tom A.; Roberts, Nicholas W.; Vinther, Jakob (2018-12-05). "Molecular palaeontology illuminates the evolution of ecdysozoan vision". Proceedings of the Royal Society B: Biological Sciences. 285 (1892): 20182180. doi:10.1098/rspb.2018.2180. ISSN 0962-8452. PMC 6283943. PMID 30518575.
  49. ^ a b c d Park, Tae-Yoon S.; Kihm, Ji-Hoon; Woo, Jusun; Park, Changkun; Lee, Won Young; Smith, M. Paul; Harper, David A. T.; Young, Fletcher; Nielsen, Arne T. (2018-03-09). "Brain and eyes of Kerygmachela reveal protocerebral ancestry of the panarthropod head". Nature Communications. 9 (1): 1019. Bibcode:2018NatCo...9.1019P. doi:10.1038/s41467-018-03464-w. ISSN 2041-1723. PMC 5844904. PMID 29523785.
  50. ^ a b c d e f Chen, J.Y., Zhou, G.Q., Ramsköld, L. (1995a). The Cambrian lobopodian Microdictyon sinicum. Bulletin of the National Museum of Natural Science 5, 1–93 (Taichung, Taiwan).
  51. ^ a b c d e f Ma, Xiaoya; Edgecombe, Gregory; Legg, David; Hou, Xianguang (2013-05-08). "The morphology and phylogenetic position of the Cambrian lobopodian Diania cactiformis". Journal of Systematic Palaeontology. 12 (4): 445–457. doi:10.1080/14772019.2013.770418. S2CID 220463025.
  52. ^ a b Steiner, M.; Hu, S.X.; Liu, J.; Keupp, H. (2012-02-02). "A new species of Hallucigenia from the Cambrian Stage 4 Wulongqing Formation of Yunnan (South China) and the structure of sclerites in lobopodians". Bulletin of Geosciences: 107–124. doi:10.3140/bull.geosci.1280. ISSN 1802-8225.
  53. ^ a b c d e f Zhang, Xi-Guang; Smith, Martin R.; Yang, Jie; Hou, Jin-Bo (2016). "Onychophoran-like musculature in a phosphatized Cambrian lobopodian". Biology Letters. 12 (9): 20160492. doi:10.1098/rsbl.2016.0492. ISSN 1744-9561. PMC 5046927. PMID 27677816.
  54. ^ a b c Liu, Jianni; Steiner, Michael; Dunlop, Jason A.; Keupp, Helmut; Shu, Degan; Ou, Qiang; Han, Jian; Zhang, Zhifei; Zhang, Xingliang (February 2011). "An armoured Cambrian lobopodian from China with arthropod-like appendages". Nature. 470 (7335): 526–530. Bibcode:2011Natur.470..526L. doi:10.1038/nature09704. ISSN 1476-4687. PMID 21350485. S2CID 4324509.
  55. ^ a b c d e Vannier, Jean; Liu, Jianni; Lerosey-Aubril, Rudy; Vinther, Jakob; Daley, Allison C. (2014-05-02). "Sophisticated digestive systems in early arthropods". Nature Communications. 5 (1): 3641. Bibcode:2014NatCo...5.3641V. doi:10.1038/ncomms4641. ISSN 2041-1723. PMID 24785191.
  56. ^ Butterfield, N. J. (2002). "Leanchoilia guts and the interpretation of three-dimensional structures in Burgess Shale-type fossils". Paleobiology. 28: 155–171. doi:10.1666/0094-8373(2002)028<0155:LGATIO>2.0.CO;2. ISSN 0094-8373. S2CID 85606166.
  57. ^ a b c d Young, Fletcher J.; Vinther, Jakob (2017). "Onychophoran-like myoanatomy of the Cambrian gilled lobopodian Pambdelurion whittingtoni" (PDF). Palaeontology. 60 (1): 27–54. Bibcode:2017Palgy..60...27Y. doi:10.1111/pala.12269. hdl:1983/92180ef0-2205-4c65-9a70-90d59cfea2f4. ISSN 1475-4983. S2CID 55477207. Archived (PDF) from the original on 2022-10-10.
  58. ^ a b c d e Budd, G. E. (2001). "Why are arthropods segmented?". Evolution and Development. 3 (5): 332–42. doi:10.1046/j.1525-142X.2001.01041.x. PMID 11710765. S2CID 37935884.
  59. ^ McCall, C. R. A. (2023). "A large pelagic lobopodian from the Cambrian Pioche Shale of Nevada". Journal of Paleontology. 97 (5): 1009–1024. doi:10.1017/jpa.2023.63.
  60. ^ a b c d Van Roy, Peter; Daley, Allison C.; Briggs, Derek E. G. (2015). "Anomalocaridid trunk limb homology revealed by a giant filter-feeder with paired flaps". Nature. 522 (7554): 77–80. Bibcode:2015Natur.522...77V. doi:10.1038/nature14256. ISSN 1476-4687. PMID 25762145. S2CID 205242881.
  61. ^ Budd, Graham E.; Daley, Allison C. (January 2012). "The lobes and lobopods of Opabinia regalis from the middle Cambrian Burgess Shale: The lobes of Opabinia". Lethaia. 45 (1): 83–95. doi:10.1111/j.1502-3931.2011.00264.x.
  62. ^ Chen, J.-y; Ramskold, L.; Zhou, G.-q (1994). "Evidence for Monophyly and Arthropod Affinity of Cambrian Giant Predators". Science. 264 (5163): 1304–1308. Bibcode:1994Sci...264.1304C. doi:10.1126/science.264.5163.1304. ISSN 0036-8075. PMID 17780848. S2CID 1913482.
  63. ^ Edgecombe, Gregory D. (2020-11-02). "Arthropod Origins: Integrating Paleontological and Molecular Evidence". Annual Review of Ecology, Evolution, and Systematics. 51 (1): 1–25. doi:10.1146/annurev-ecolsys-011720-124437. ISSN 1543-592X. S2CID 225478171.
  64. ^ Whittle, R. J.; Gabbott, S. E.; Aldridge, R. J.; Theron, J. (2009). "An Ordovician Lobopodian from the Soom Shale Lagerstätte, South Africa". Palaeontology. 52 (3): 561–567. Bibcode:2009Palgy..52..561W. doi:10.1111/j.1475-4983.2009.00860.x. S2CID 129609503.
  65. ^ Edgecombe, Gregory D. (2009-06-01). "Palaeontological and Molecular Evidence Linking Arthropods, Onychophorans, and other Ecdysozoa". Evolution: Education and Outreach. 2 (2): 178–190. doi:10.1007/s12052-009-0118-3. ISSN 1936-6434.
  66. ^ Robison, R. A. (1985). "Affinities of Aysheaia (Onychophora), with Description of a New Cambrian Species". Journal of Paleontology. 59 (1): 226–235. ISSN 0022-3360. JSTOR 1304837.
  67. ^ Bergström, J.; Hou, Xian-Guang (2001-12-01). "Cambrian Onychophora or Xenusians". Zoologischer Anzeiger. 240 (3–4): 237–245. doi:10.1078/0044-5231-00031.
  68. ^ a b Budd, Graham E. (2001-01-01). "Tardigrades as 'Stem-Group Arthropods': The Evidence from the Cambrian Fauna". Zoologischer Anzeiger - A Journal of Comparative Zoology. 240 (3): 265–279. doi:10.1078/0044-5231-00034. ISSN 0044-5231.
  69. ^ Mounce, Ross C. P.; Wills, Matthew A. (August 2011). "Phylogenetic position of Diania challenged". Nature. 476 (7359): E1, discussion E3–4. Bibcode:2011Natur.476E...1M. doi:10.1038/nature10266. ISSN 1476-4687. PMID 21833044. S2CID 4417903.
  70. ^ Legg, David; Ma, Xiaoya; Wolfe, Joanna; Ortega-Hernández, Javier; Edgecombe, Gregory; Sutton, Mark (2011-08-11). "Lobopodian phylogeny reanalysed". Nature. 476 (7359): E2–3, discussion E3. Bibcode:2011Natur.476Q...1L. doi:10.1038/nature10267. PMID 21833046. S2CID 4310063.
  71. ^ Maas, Andreas; Waloszek, Dieter (2001-01-01). "Cambrian Derivatives of the Early Arthropod Stem Lineage, Pentastomids, Tardigrades and Lobopodians An 'Orsten' Perspective". Zoologischer Anzeiger - A Journal of Comparative Zoology. 240 (3): 451–459. doi:10.1078/0044-5231-00053. ISSN 0044-5231.
  72. ^ Kihm, Ji-Hoon; Smith, Frank W.; Kim, Sanghee; Rho, Hyun Soo; Zhang, Xingliang; Liu, Jianni; Park, Tae-Yoon S. (2023). "Cambrian lobopodians shed light on the origin of the tardigrade body plan". Proceedings of the National Academy of Sciences. 120 (28): e2211251120. doi:10.1073/pnas.2211251120. PMC 10334802. PMID 37399417.
  73. ^ Pates, Stephen; Daley, Allison C. (2017). "Caryosyntrips: a radiodontan from the Cambrian of Spain, USA and Canada". Papers in Palaeontology. 3 (3): 461–470. doi:10.1002/spp2.1084. ISSN 2056-2802. S2CID 135026011.
  74. ^ "Aysheaia prolata from the Utah Wheeler Formation (Drumian, Cambrian) is a frontal appendage of the radiodontan Stanleycaris - Acta Palaeontologica Polonica". www.app.pan.pl. Retrieved 2020-01-08.
  75. ^ "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". www.app.pan.pl. Retrieved 2020-01-08.
  76. ^ Liu, Jianni; Shu, DeGan; Han, Jian; Zhang, Zhifei (2008-05-01). "Comparative study of Cambrian lobopods Miraluolishania and Luolishania". Chinese Science Bulletin. 53 (1): 87–93. Bibcode:2008ChSBu..53...87L. doi:10.1007/s11434-007-0428-1. S2CID 128619311.
  77. ^ a b Xianguang, Hou; Ramsköld, Lars; Bergström, Jan (1991). "Composition and preservation of the Chengjiang fauna –a Lower Cambrian soft-bodied biota". Zoologica Scripta. 20 (4): 395–411. doi:10.1111/j.1463-6409.1991.tb00303.x. ISSN 1463-6409. S2CID 85077111.
  78. ^ Yang, Jie; Ortega-Hernández, Javier; Gerber, Sylvain; Butterfield, Nicholas J.; Hou, Jin-bo; Lan, Tian; Zhang, Xi-guang (2015-07-14). "A superarmored lobopodian from the Cambrian of China and early disparity in the evolution of Onychophora". Proceedings of the National Academy of Sciences. 112 (28): 8678–8683. Bibcode:2015PNAS..112.8678Y. doi:10.1073/pnas.1505596112. ISSN 0027-8424. PMC 4507230. PMID 26124122.
  79. ^ Aria, C.; Caron, J.-B. (2024). "Deep origin of articulation strategies in panarthropods: evidence from a new luolishaniid lobopodian (Panarthropoda) from the Tulip Beds, Burgess Shale". Journal of Systematic Palaeontology. 22 (1). 2356090. Bibcode:2024JSPal..2256090A. doi:10.1080/14772019.2024.2356090.
  80. ^ a b Zhang, Xi-Guang; Aldridge, Richard J. (2007). "Development and Diversification of Trunk Plates of the Lower Cambrian Lobopodians". Palaeontology. 50 (2): 401–415. Bibcode:2007Palgy..50..401Z. doi:10.1111/j.1475-4983.2006.00634.x. ISSN 1475-4983. S2CID 85293118.
  81. ^ BUDD, G. E., PEEL, J. S. (1998). A new xenusiid lobopod from the Early Cambrian Sirius Passet fauna of North Greenland. Palaeontology, 41, 6, 1201–1213.
  82. ^ Luo, H. L., Hu, S. X. & Chen, L. Z. Early Cambrian Chengjiang Fauna from Kunming Region, China. 129 (Yunnan Science and Technology Press, 1999).
  83. ^ a b McCall, Christian (13 December 2023). "A large pelagic lobopodian from the Cambrian Pioche Shale of Nevada". Journal of Paleontology. 97 (5): 1009–1024. doi:10.1017/jpa.2023.63. Retrieved 13 December 2023.
  84. ^ Hou, Xianguang; Bergström, Jan; Jie, Yang (2006). "Distinguishing anomalocaridids from arthropods and priapulids". Geological Journal. 41 (3–4): 259–269. Bibcode:2006GeolJ..41..259X. doi:10.1002/gj.1050. S2CID 83582128.
  85. ^ Maas, Andreas; Mayer, Georg; Kristensen, Reinhardt M.; Waloszek, Dieter (2007-12-01). "A Cambrian micro-lobopodian and the evolution of arthropod locomotion and reproduction". Chinese Science Bulletin. 52 (24): 3385–3392. Bibcode:2007ChSBu..52.3385M. doi:10.1007/s11434-007-0515-3. ISSN 1861-9541. S2CID 83993887.
  86. ^ Jun-yuan, Chen; Gui-qing, Zhou; Ramsköld, Lars (1994). "A new Early Cambrian onychophoran-like animal, Paucipodia gen. nov., from the Chengjiang fauna, China". Earth and Environmental Science Transactions of the Royal Society of Edinburgh. 85 (4): 275–282. doi:10.1017/S0263593300002042. ISSN 1473-7116. S2CID 131555757.
  87. ^ Lerosey-Aubril, R.; Ortega-Hernández, J. (2022). "A new lobopodian from the middle Cambrian of Utah: did swimming body flaps convergently evolve in stem-group arthropods?". Papers in Palaeontology. 8 (3): e1450. doi:10.1002/spp2.1450. S2CID 250076505.
  88. ^ Smith, Martin R.; Long, Emma J.; Dhungana, Alavya; Dobson, Katherine J.; Yang, Jie; Zhang, Xiguang (2024). "Organ systems of a Cambrian euarthropod larva". Nature. 624: 123–128. doi:10.1038/s41586-024-07756-8.