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Wiwaxia


Wiwaxia
Temporal range: Early Cambrian to Middle Cambrian (Stage 3 to Wuliuan), Possible record of Late Cambrian and Ordovician period
Fossil showing underside of Wiwaxia corrugata from the Burgess Shale. From Smith (2014).
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Superphylum: Lophotrochozoa
Phylum: Mollusca (?)
Family: †Wiwaxiidae
Walcott, 1911
Genus: †Wiwaxia
Walcott, 1911
Species
  • W. corrugata (Matthew, 1899) (type)
  • W. foliosa Yang et al., 2014[2]
  • W. papilio Zhang, Smith & Shu, 2015[3]
  • W. taijiangensis Zhao, Qian & Lee, 1994[4]
  • W. sp. See Butterfield 1994, Smith 2014, Smith, Hughes et al., 2015
  • W. herka Conway Morris et al., 2015[5]

Wiwaxia is a genus of soft-bodied animals that were covered in carbonaceous scales and spines that protected it from predators. Wiwaxia fossils – mainly isolated scales, but sometimes complete, articulated fossils – are known from early Cambrian and middle Cambrian fossil deposits across the globe.[4][6][7] The living animal would have measured up to 5 cm (2 inch) when fully grown, although a range of juvenile specimens are known, the smallest being 2 millimetres (0.079 in) long.[7]

Wiwaxia's affinity has been a matter of debate: Researchers were long split between two possibilities. On the one hand, its rows of scales looked superficially similar to certain scale worms (annelids); conversely, its mouthparts and general morphology suggested a relationship to the shell-less molluscs. More recently, evidence for a molluscan affinity has been accumulating, based on new details of Wiwaxia's mouthparts, scales, and growth history.[7][8]

The proposed clade Halwaxiida contains Wiwaxia as well as several similar Cambrian animals.

  1. ^ Cite error: The named reference Kimming-etal-2019 was invoked but never defined (see the help page).
  2. ^ Cite error: The named reference Yang-etal-2014 was invoked but never defined (see the help page).
  3. ^ Cite error: The named reference Zhang-Smith-Shu-2015 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference Zhao1994 was invoked but never defined (see the help page).
  5. ^ Morris, Simon Conway; Selden, Paul A.; Gunther, Glade; Jamison, Paul G.; Robison, Richard A. (2015). "New records of Burgess Shale-type taxa from the middle Cambrian of Utah". Journal of Paleontology. 89 (3): 411–423. Bibcode:2015JPal...89..411C. doi:10.1017/jpa.2015.26. ISSN 0022-3360. S2CID 55050961.
  6. ^ Cite error: The named reference ConwayMorris1985 was invoked but never defined (see the help page).
  7. ^ a b c Cite error: The named reference Smith2014 was invoked but never defined (see the help page).
  8. ^ Smith, M.R. (2012). "Mouthparts of the Burgess Shale fossils Odontogriphus and Wiwaxia: Implications for the ancestral molluscan radula". Proceedings of the Royal Society B. 279 (1745): 4287–4295. doi:10.1098/rspb.2012.1577. PMC 3441091. PMID 22915671.

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