Xenusiid

Xenusiid; Temporal range: ; Early Cambrian to Carboniferous PreꞒ Ꞓ O S D C P T J K Pg N
	Hallucigenia sparsa
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
(unranked):	Panarthropoda
Phylum:	†"Lobopodia"
Class:	†Xenusia; Dzik & Krumbiegel, 1989
Orders
	See text.

Class Xenusia, the Xenusiids, represents the subset of lobopodian worms that fall in the stem-lineage of Onychophora.^[2] Their type genus is Xenusion.^[3] They have relatively large, annulated, cylindrical body. Their lobopod legs have tubercles at their bases. Some have large frontal appendages,^[3] although these may represent taphonomic artefacts.^[4] Their mouth is terminal or subterminal, and they are marine.^[5] They probably represent a grade (paraphyletic group) rather than a clade (monophyletic group).

Systematics

Xenusia includes the following orders and families:^[5]

Order Archonychophora

Archonychophora Hou & Bergstrom, 1995^[2] - Undifferentiated appendages; each segment the same as each other. See ^[6]
- Luolishaniidae Hou & Bergstrom, 1995 - three small rounded sclerites per segment - these are thorn-shaped spines.^[6]
  - Luolishania Hou & Chen 1989
  - Miraluolishania Liu & Shu 2004
- Paucipodiidae Hou et al., 2004^[7] - with no dorsal sclerites, two claws, fine annulation and few segments.
  - Paucipodia Hou et al. 2004

These taxa are only known from the Chengjiang (Cambrian Stage 2 Series 3).

Order Protonychophora

Protonychophora Hutchinson, 1930 - Spiny legs, reduced tail
- Aysheaiidae Walcott, 1911 - many claws on each leg. Anterior grasping appendages with long spines.
  - Aysheaia Walcott 1911
- Xenusiidae Dzik & Krumbiegel, 1989 - >20 leg-bearing segments; paired, rounded sclerites on each segment; spiny legs.
  - Xenusion Pompeckj, 1927
  - Jianshanopodia Liu et al ^[8] - from Chengjiang; two rows of tubercles but no obvious sclerites
  - Hadranax Budd & Peel 1998 — from the Sirius Passet. Lacks obvious dorsal armature, but bears four 'nodes' per row.

Order Scleronychophora

Scleronychophora Hou & Bergstrom, 1995 - paired sclerites; elongated head sclerites
- Eoconchariidae Hou & Shu, 1987 - ~10 leg-bearing segments, small head, sieve-like sclerites, varying in shape along body; curved claws on annulated legs; terminal mouth and anus.
  - Microdictyon Bengtson et al
  - Quadratapora
- Hallucigeniidae Conway Morris, 1977 - ~10 leg-bearing segments; large sclerites covering head; sclerites on each segment are long spines.
  - Hallucigenia Conway Morris 1977 - From the Chengjiang, Kaili and Burgess Shale^[9]
- Cardiodictyidae Hou & Bergstrom, 1995 - many segments (~23); large sclerites cover head; hexagonal sclerite on each body segment.
  - Cardiodictyon Hou et al 1991 - Known from the Chengjiang^[9]

Order Paronychophora

Paronychophora Hou & Bergstrom, 1995 - short, downwards facing head; papillae on body and legs, some arranged in rows; shield-like sclerites on head; dorsal armature of spines;^[10] claw-like jaws; annulated legs
- Onychodictyidae Hou & Bergstrom, 1995
  - Onychodictyon Hou et al 1991

Order unassigned

Orstenotubulus Maas et al 2007 from the Furongian Orsten deposits - with retractable dorsal spines^[11]
Carbotubulus Haug et al 2012 ^[12] - from the Mazon creek. Dorwal armature uncertain. Few segments, long limbs.
Mureropodia,^[13] from the Stage 2 Murero lagerstatten, Spain

'Phylum' Onychophora

Onychophora are distinguished by their terrestrial habit, their ventral mouth; their antennae, jaws and oral papillae; they seem to be most closely related to the Paronychophora. Their first fossils are Carboniferous (Helenodora), although they may have had a cryptic earlier history.

References

^ Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1111/j.1502-3931.1989.tb01679.x, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1111/j.1502-3931.1989.tb01679.x instead.
^ ^a ^b Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1111/j.1096-3642.1995.tb00110.x, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1111/j.1096-3642.1995.tb00110.x instead.
^ ^a ^b 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 Palaeontologica Polonica. 51 (2): 215–222.{{cite journal}}: CS1 maint: multiple names: authors list (link)
^ Julián Monge-Nájera & Xianguang Hou (2002). "Experimental taphonomy of velvet worms (Onychophora) and implications for the Cambrian "explosion, disparity and decimation" model" (PDF). Revista de Biología Tropical. 50 (3–4): 1133–1138. PMID 12947596.
^ ^a ^b George Poinar, Jr. (2000). "Fossil onychophorans from Dominican and Baltic amber: Tertiapatus dominicanus n.g., n.sp. (Tertiapatidae n.fam.) and Succinipatopsis balticus n.g., n.sp. (Succinipatopsidae n.fam.) with a proposed classification of the subphylum Onychophora". Invertebrate Biology. 119 (1): 104–109. doi:10.1111/j.1744-7410.2000.tb00178.x. JSTOR 3227105.
^ ^a ^b Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1016/j.asd.2009.03.001, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1016/j.asd.2009.03.001 instead.
^ Xian-Guang Hou, Xiao-Ya Ma, Jie Zhao & Jan Bergström (2004). "The lobopodian Paucipodia inermis from the Lower Cambrian Chengjiang fauna, Yunnan, China". Lethaia. 37 (3): 235–244. doi:10.1080/00241160410006555.{{cite journal}}: CS1 maint: multiple names: authors list (link)
^ http://www.app.pan.pl/article/item/app51-215.html. {{cite journal}}: Cite journal requires |journal= (help); Missing or empty |title= (help)
^ ^a ^b Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1111/j.1475-4983.2009.00860.x, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1111/j.1475-4983.2009.00860.x instead.
^ Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.4202/app.2008.0209, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.4202/app.2008.0209 instead.
^ Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1007/s11434-007-0515-3, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1007/s11434-007-0515-3 instead.
^ Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1016/j.cub.2012.06.066, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1016/j.cub.2012.06.066 instead.
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[Dzik1989-1] Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1111/j.1502-3931.1989.tb01679.x, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1111/j.1502-3931.1989.tb01679.x instead.

[Hou1995-2] Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1111/j.1096-3642.1995.tb00110.x, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1111/j.1096-3642.1995.tb00110.x instead.

[Liu2006-3] 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 Palaeontologica Polonica. 51 (2): 215–222.{{cite journal}}: CS1 maint: multiple names: authors list (link)

[4] Julián Monge-Nájera & Xianguang Hou (2002). "Experimental taphonomy of velvet worms (Onychophora) and implications for the Cambrian "explosion, disparity and decimation" model" (PDF). Revista de Biología Tropical. 50 (3–4): 1133–1138. PMID 12947596.

[Poinar2000-5] George Poinar, Jr. (2000). "Fossil onychophorans from Dominican and Baltic amber: Tertiapatus dominicanus n.g., n.sp. (Tertiapatidae n.fam.) and Succinipatopsis balticus n.g., n.sp. (Succinipatopsidae n.fam.) with a proposed classification of the subphylum Onychophora". Invertebrate Biology. 119 (1): 104–109. doi:10.1111/j.1744-7410.2000.tb00178.x. JSTOR 3227105.

[Ma2009-6] Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1016/j.asd.2009.03.001, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1016/j.asd.2009.03.001 instead.

[7] Xian-Guang Hou, Xiao-Ya Ma, Jie Zhao & Jan Bergström (2004). "The lobopodian Paucipodia inermis from the Lower Cambrian Chengjiang fauna, Yunnan, China". Lethaia. 37 (3): 235–244. doi:10.1080/00241160410006555.{{cite journal}}: CS1 maint: multiple names: authors list (link)

[8] ttp://www.app.pan.pl/article/item/app51-215.html. {{cite journal}}: Cite journal requires |journal= (help); Missing or empty |title= (help)

[Whittle2009-9] Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1111/j.1475-4983.2009.00860.x, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1111/j.1475-4983.2009.00860.x instead.

[Liu2008-10] Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.4202/app.2008.0209, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.4202/app.2008.0209 instead.

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[Haug2012-12] Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1016/j.cub.2012.06.066, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1016/j.cub.2012.06.066 instead.

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