Nephrozoa

Nephrozoa is a major clade of bilaterians, divided into the protostomes and the deuterostomes, containing almost all animal phyla and over a million extant species. Its sister clade is the Xenacoelomorpha. The Ambulacraria (conventionally deuterostomes) was formerly thought to be sister to the Xenacoelomorpha, forming the Xenambulacraria as basal Deuterostomes, or basal Bilateria invalidating Nephrozoa and Deuterostomes in earlier studies.[1][2][3] The coelom, the digestive tract and excretory organs, and nerve cords developed in the Nephrozoa.[4] It has been argued that, because protonephridia are only found in protostomes, they can not be considered a synapomorphy of this group. This would make Nephrozoa an improper name, leaving Eubilateria as this clade's name.[5]

Nephrozoa
Temporal range: Ediacaran - Present, 558–0 Ma
Diversity of nephrozoans
Scientific classification
Kingdom: Animalia
Subkingdom: Eumetazoa
Clade: ParaHoxozoa
Clade: Bilateria
Clade: Nephrozoa
Jondelius et al. , 2002
Phyla
Synonyms

Eubilateria Peter Ax, 1987

Chordates (which include all the vertebrates) are deuterostomes.[6] It seems very likely that the 555 million year old Kimberella was a member of the protostomes.[7][8] If so, this means that the protostome and deuterostome lineages must have split some time before Kimberella appeared — at least 558 million years ago, and hence well before the start of the Cambrian 541 million years ago.[6]


Bilateria
 

Xenacoelomorpha

 
Nephrozoa
Deuterostomia
 

Chordata

525 mya
Ambulacraria
 

Echinodermata

 
 

Hemichordata

 
 
 
Protostomia
 

Ecdysozoa

 
 

Spiralia

 
610 mya
650 mya
 

References
  1. Philippe, Hervé; Poustka, Albert J.; Chiodin, Marta; Hoff, Katharina J.; Dessimoz, Christophe; Tomiczek, Bartlomiej; Schiffer, Philipp H.; et al. (2019). "Mitigating Anticipated Effects of Systematic Errors Supports Sister-Group Relationship between Xenacoelomorpha and Ambulacraria". Current Biology. 29 (11): 1818–1826.e6. doi:10.1016/j.cub.2019.04.009. hdl:21.11116/0000-0004-DC4B-1. ISSN 0960-9822. PMID 31104936. S2CID 155104811.
  2. Marlétaz, Ferdinand (2019-06-17). "Zoology: Worming into the Origin of Bilaterians". Current Biology. 29 (12): R577–R579. doi:10.1016/j.cub.2019.05.006. ISSN 0960-9822. PMID 31211978.
  3. Kapli, Paschalia; Telford, Maximilian J. (11 Dec 2020). "Topology-dependent asymmetry in systematic errors affects phylogenetic placement of Ctenophora and Xenacoelomorpha". Science Advances. 6 (10). doi:10.1126/sciadv.abc5162. Retrieved 17 December 2020.
  4. Cannon, Johanna Taylor; Vellutini, Bruno Cossermelli; Smith, Julian; Ronquist, Fredrik; Jondelius, Ulf; Hejnol, Andreas (2016). "Xenacoelomorpha is the sister group to Nephrozoa". Nature. 530 (7588): 89–93. Bibcode:2016Natur.530...89C. doi:10.1038/nature16520. PMID 26842059. S2CID 205247296.
  5. "Animal Evolution: Interrelationships of the Living Phyla. Third Edition. By Claus Nielsen. Oxford and New York: Oxford University Press ISBN: 978-0-19-960602-3 (hc); 978-0-19-960603-0 (pb). 2012". The Quarterly Review of Biology. 87 (3): 258. September 2012. doi:10.1086/666815. ISSN 0033-5770.
  6. Erwin, Douglas H.; Eric H. Davidson (1 July 2002). "The last common bilaterian ancestor". Development. 129 (13): 3021–3032. PMID 12070079.
  7. New data on Kimberella, the Vendian mollusc-like organism (White sea region, Russia): palaeoecological and evolutionary implications (2007), "Fedonkin, M.A.; Simonetta, A; Ivantsov, A.Y.", in Vickers-Rich, Patricia; Komarower, Patricia (eds.), The Rise and Fall of the Ediacaran Biota, Special publications, 286, London: Geological Society, pp. 157–179, doi:10.1144/SP286.12, ISBN 9781862392335, OCLC 156823511CS1 maint: uses authors parameter (link)
  8. Butterfield, N.J. (December 2006). "Hooking some stem-group "worms": fossil lophotrochozoans in the Burgess Shale". BioEssays. 28 (12): 1161–6. doi:10.1002/bies.20507. PMID 17120226. S2CID 29130876.

Further reading
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