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Vetulicolia

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Vetulicolia
Temporal range: about520–501MaCambrian Stage 3—Drumian- PossibleEdiacaranrecord[1]
Fossil ofVetulicola cuneata
Scientific classificationEdit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade?: †Vetulicolia
Shuet al.2001
Type species
†Vetulicola cuneata
Hou, 1987
Classes
  • †Banffozoa?
  • †Vetulicolida

Vetulicolia[note 1]is acladeofbilateriananimalsencompassing severalextinctspecies belonging to theCambrian period.[2][3]The clade was created by Degan Shu and his research team in 2001,[4]and named afterVetulicola cuneata,the first species of the phylum described in 1987.[5]

The vetulicolianbody plancomprises two parts: a voluminousrostral(anterior) forebody, tipped with an anteriorly positionedmouthand lined with a lateral row of five round to oval-shaped openings on each side, which have been interpreted asgills(or at leastorificesin the vicinity of thepharynx); and acaudal(posterior) section that primitively comprises sevenbody segmentsand functions as atail.All vetulicolians lack preservedappendagesof any kind, having no legs, feelers or eveneye spots.[6]The area where the anterior and posterior parts join is constricted.[7]

Theirtaxonomicaffinity has been uncertain; they have been interpreted asstem- andcrown-grouparthropods,stem-groupvertebrates,[8]and earlydeuterostomes(a group which as a whole includes the vertebrates, otherinvertebratechordates,echinodermsandhemichordates). The general scientific consensus before 2001 considered them early limblessarthropodsbut now considers them early deuterostomes.[9]Vetulicolian fossils examined in 2014 show the presence ofnotochord-like structures, and it was concluded that vetulicolians are crown-groupchordatesand probably related to moderntunicates.[10]Research from 2017 rather indicates vetulicolians are related toSaccorhytus,another basal deuterostome group,[11]although another study shows possibility thatSaccorhytusisecdysozoaninstead of deuterostome.[12]A 2024 paper, however, found vetulicolians to be a paraphyletic group at the base of Chordata.[13]Banffozoa’s inclusion within this group is dubious, due to their lack of gill slits and apparent gut diverticula, and so they may be within Protostomia instead.[14]

Taxonomy and evolution

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See also:List of bilaterial animal orders

Vetulicolia as a phylum was created by Chinese palaeontologist Degan Shu and his research team at theNorthwest Universityin Xi'an, China, along withSimon Conway Morrisat theUniversity of Cambridgein 2001.[4]The name was derived fromVetulicola cuneata,the first species described byHou Xian-guangin 1987 from the Lower CambrianChiungchussu Formation in Chengjiang,China.[3][5]The purpose was to include all related Cambrian animals known under the familiesDidazoonidae(Didazoon,Pomatrum,andXidazoon) andVetulicolidae(Vetulicola,andBanffia) as a separate group of animals.[2][4]Other animals which may be related include theyunnanozoans.[4]

The taxonomic placement of the vetulicolians remains controversial. The original researcher Shu is of the opinion that the vetulicolians probably represent an early type of deuterostomes, and that this implies that segmentation incephalochordatesandvertebratesmay be derived from the common ancestor ofprotostomesand deuterostomes.[8]However,Derek BriggsofYale Universityand his team who describedSkeemellafrom the Middle Cambrian of Utah regard it as having affinity to protostomes with importantarthropodfeatures, thus confounding assignment of Vetulicolia to Deuterostomia.[15]Thurston C. Lacalli of theUniversity of Saskatchewan,Saskatoon, Canada, agreed that the group are deuterostomes, but suggested that the animals were more likely related totunicates.[16]

Dominguez and Jefferies have argued, based onmorphologicalanalysis, thatVetulicola(and by implication, other vetulicolians) is aurochordate,and probably a stem-grouplarvacean.Some question the relation to tunicates and larvaceans, as there is no evidence of segmentation in tunicates, larval or adult, that is comparable to segmentation in vetulicolians, that the anus of urochordates is within the atrium, while that of vetulicolians is positioned at the terminal end of the tail, and, perhaps most importantly, there is no exhalant siphon, or analogous structure, seen in vetulicolians.[17]However, a discovery of a new vetulicolian,Nesonektris aldridgei,from Australia in 2014 supported a position close to urochordates for vetulicolians.[10]

A 2024 phylogenetic analysis by Mussini and colleagues found vetulicolians to be aparaphyleticgroup ofstem-chordates, lying outside a clade formed byYunnanozoon,Cathaymyrus,Pikaiaandcrown-chordates.[13]

Chordata
Vetulicolia

Ecology and lifestyle

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Fossil ofSkeemella clavula

From their superficially tadpole-like forms, leaf or paddle-shaped tails, and various degrees of streamlining, it is assumed that all vetulicolians discovered to date were swimming animals that spent much, if not all, of their time living in water.[17]Some groups, like the genusVetulicola,were more streamlined (complete with ventralkeels) than other groups, such as the tadpole-like Didazoonidae.[17]

Because all vetulicolians had mouths which had no features for chewing or grasping, it is assumed that they were not predators.[17]Since vetulicolians possessed gill slits, many researchers regard these organisms asplanktivores.The sediment infills in the guts of their fossils have caused some to suggest that they were deposit feeders. This idea has been contested, as deposit feeders tend to have straight guts, whereas the hindguts of vetulicolians were spiral-shaped. Some researchers propose that the vetulicolians were "selective deposit-feeders" which actively swam from one region of the seafloor to another, while supplementing their nutrition with filter-feeding.[17]

Classification

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Notes

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  1. ^The taxon name, Vetulicolia, is derived from the type genus,Vetulicola,which is a compoundLatinword composed ofvetuli"old" andcola"inhabitant".

References

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  1. ^Liu, Junping; Chen, Ailin; Li, Binglin; Tang, Feng; Zhao, Jiangtai; Chen, Ke (2024-10-06). "Problematic Ediacaran sail-shaped fossils from eastern Yunnan, China".Historical Biology.Informa UK Limited: 1–7.doi:10.1080/08912963.2024.2403588.ISSN0891-2963.
  2. ^abShu, Degan (2005)."On the Phylum Vetulicolia".Chinese Science Bulletin.50(20): 2342–2354.Bibcode:2005ChSBu..50.2342S.doi:10.1007/BF03183746.ISSN1001-6538.S2CID86827605.
  3. ^abMcMenamin, Mark A. S. (2019)."Cambrian Chordates and Vetulicolians".Geosciences.9(8): 354.Bibcode:2019Geosc...9..354M.doi:10.3390/geosciences9080354.ISSN2076-3263.
  4. ^abcdShu, D. G.; Conway Morris, S.; Han, J.; Chen, L.; Zhang, X. L.; Zhang, Z. F.; Liu, H. Q.; Li, Y.; Liu, J. N. (2001-11-22). "Primitive deuterostomes from the Chengjiang Lagerstätte (Lower Cambrian, China)".Nature.414(6862): 419–424.Bibcode:2001Natur.414..419S.doi:10.1038/35106514.ISSN0028-0836.PMID11719797.S2CID4345484.
  5. ^abBriggs, Derek E. G.; Fortey, Richard A. (2005)."Wonderful strife: systematics, stem groups, and the phylogenetic signal of the Cambrian radiation".Paleobiology.31(2_Suppl): 94–112.doi:10.1666/0094-8373(2005)031[0094:WSSSGA]2.0.CO;2.ISSN0094-8373.S2CID44066226.
  6. ^Ailin, C.; Hongzhen, F.; Maoyan, Z.H.U.; Dongsheng, M.A.; Ming, L.I. (2003),"A New Vetulicolian from the Early Cambrian Chengjiang Fauna in Yunnan of China",Acta Geologica Sinica,77(3): 281–287,doi:10.1111/j.1755-6724.2003.tb00742.x,S2CID128895860[dead link‍]
  7. ^abMcMenamin, Mark A. S. (11 August 2019)."Cambrian Chordates and Vetulicolians".Geosciences.9(8): 354.Bibcode:2019Geosc...9..354M.doi:10.3390/geosciences9080354.
  8. ^abShu, Degan (2003). "A paleontological perspective of vertebrate origin".Chinese Science Bulletin.48(8): 725–735.Bibcode:2003ChSBu..48..725S.doi:10.1007/BF03187041.S2CID85163902.
  9. ^Dominguez, Patricio and Jeffries, Richard. (2003). Fossil evidence on the origin of appendicularians. Paper read at International Urochordate Meeting 2003. Abstract at [2] – URL retrieved June 22, 2006.
  10. ^abcGarcía-Bellido, Diego C; Paterson, John R (2014)."A new vetulicolian from Australia and its bearing on the chordate affinities of an enigmatic Cambrian group".BMC Evolutionary Biology.14:214.doi:10.1186/s12862-014-0214-z.PMC4203957.PMID25273382.
  11. ^Han, Jian;Conway Morris, Simon;Ou, Qiang; Shu, Degan; Huang, Hai (2017). "Meiofaunal deuterostomes from the basal Cambrian of Shaanxi (China)".Nature.542(7640): 228–231.Bibcode:2017Natur.542..228H.doi:10.1038/nature21072.PMID28135722.S2CID353780.
  12. ^Liu, Yunhuan; Carlisle, Emily; Zhang, Huaqiao; Yang, Ben; Steiner, Michael; Shao, Tiequan; Duan, Baichuan; Marone, Federica; Xiao, Shuhai; Donoghue, Philip C. J. (2022-08-17)."Saccorhytus is an early ecdysozoan and not the earliest deuterostome".Nature.609(7927): 541–546.Bibcode:2022Natur.609..541L.doi:10.1038/s41586-022-05107-z.hdl:1983/454e7bec-4cd4-4121-933e-abeab69e96c1.ISSN1476-4687.PMID35978194.S2CID251646316.
  13. ^abMussini, G.; Smith, M. P.; Vinther, J.; Rahman, I. A.; Murdock, D. J. E.; Harper, D. A. T.; Dunn, F. S. (2024)."A new interpretation ofPikaiareveals the origins of the chordate body plan ".Current Biology.34(13): 2980–2989.e2.doi:10.1016/j.cub.2024.05.026.PMID38866005.
  14. ^abCaron, Jean-Bernard (June 2005). "Banffia constricta, a putative vetulicolid from the Middle Cambrian Burgess Shale".Transactions of the Royal Society of Edinburgh: Earth Sciences.96(2): 95–111.doi:10.1017/S0263593300001255.
  15. ^Briggs; et al. (2005)."A new metazoan from the Middle Cambrian of Utah and the nature of the Vetulicolia".Palaeontology.48(4): 681–686.doi:10.1111/j.1475-4983.2005.00489.x.
  16. ^Lacalli, Thurston C. (2002)."Vetulicolians—are they deuterostomes? chordates?".BioEssays.24(3): 208–211.doi:10.1002/bies.10064.PMID11891757.
  17. ^abcdefAldridge, Richard J.; Hou, Xian-guang; Siveter, David J.; Siveter, Derek J.; Sarah E., Gabbott (2007). "The systematics and phylogenetic relationships of vetulicolians".Palaeontology.50:131–168.doi:10.1111/j.1475-4983.2006.00606.x.S2CID85722738.
  18. ^Liu, Junping; Chen, Ailin; Li, Binglin; Tang, Feng; Zhao, Jiangtai; Chen, Ke (6 October 2024). "Problematic Ediacaran sail-shaped fossils from eastern Yunnan, China".Historical Biology:1–7.doi:10.1080/08912963.2024.2403588.
  19. ^Vinther, J.; Smith, M. P.;Harper, D. A. T.(2011). "Vetulicolians from the Lower Cambrian Sirius Passet Lagerstätte, North Greenland, and the polarity of morphological characters in basal deuterostomes".Palaeontology.54(3): 711–719.doi:10.1111/j.1475-4983.2011.01034.x.S2CID85602402.
  20. ^Chen, Feng, Ma, Li (2003). "A New Vetulicolian from the Early Cambrian Chengjiang Fauna in Yunnan of China".Acta Geologica Sinica.77(3): 281–287.doi:10.1111/j.1755-6724.2003.tb00742.x.S2CID128895860.{{cite journal}}:CS1 maint: multiple names: authors list (link)
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