Wiwaxia

Wiwaxia
Temporal range: Early Cambrian to Middle Cambrian (Stage 3 to Wuliuan), 520–505 Ma[1] 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. herka Conway Morris et al., 2015[5]
  • W. douposiensis Sun et al., 2024

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 centimetres (2 in) when fully grown, although a range of juvenile specimens are known, the smallest being 2 millimetres (0.08 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 name derives from Wiwaxy Peak in British Columbia.[9]

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. ^ Zhang, Zhifei; Smith, Martin R.; Shu, Degan (2015). "New reconstruction of the Wiwaxia scleritome, with data from Chengjiang juveniles". Scientific Reports. 5: 14810. Bibcode:2015NatSR...514810Z. doi:10.1038/srep14810. PMC 4595806. PMID 26443243.
  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.
  9. ^ "Wiwaxia corrugata". Burgess Shale. Royal Ontario Museum.