Wiwaxia Fossil range: Middle Cambrian
Conservation status
Extinct (fossil)
Scientific classification
Kingdom: Animalia Phylum:  ?Mollusca (unranked) Halwaxiida Family: Wiwaxiidae Walcott, 1911 Genus: Wiwaxia
Binomial name
Wiwaxia corrugata Walcott, 1911

Wiwaxia corrugata is an extinct species of animal known only from fossils found in Canada's Burgess Shale deposits. Although Wiwaxia resembles a mollusk in having a well developed radula, it does not really fit the conchifera because of its sclerites (armor of flattened, chitinous spines), but rather the class Aplacophora. The actual classification of Wiwaxia in the animal kingdom is still controversial. The Middle Cambrian is an geological epoch that is part of the Cambrian Era. ... Image File history File linksMetadata Wiwaxia_corrugata. ... The conservation status of a species is an indicator of the likelihood of that species continuing to survive either in the present day or the future. ... Three small ammonite fossils, each approximately 1. ... Scientific classification or biological classification is a method by which biologists group and categorize species of organisms. ... Animalia redirects here. ... Classes Caudofoveata Aplacophora Polyplacophora Monoplacophora Bivalvia Scaphopoda Gastropoda Cephalopoda † Rostroconchia † Helcionelloida The molluscs (British spelling) or mollusks (American spelling) are the large and diverse phylum Mollusca, which includes a variety of familiar animals well-known for their decorative shells or as seafood. ... In biology, binomial nomenclature is the formal method of naming species. ... Three small ammonite fossils, each approximately 1. ... The Burgess Shale (named after Mount Burgess, close to where the Shale was found) is a black shale exposure found high up in the Canadian Rockies in Yoho National Park near the town of Field, British Columbia. ... Classes Caudofoveata Aplacophora Polyplacophora Monoplacophora Bivalvia Scaphopoda Gastropoda Cephalopoda † Rostroconchia The mollusks or molluscs are the large and diverse phylum Mollusca, which includes a variety of familiar creatures well-known for their decorative shells or as seafood. ... Radula is the scientific name for the toothed chitinous ribbon in the mouth of gastropods. ... Classes Scaphopoda Cephalopoda Bivalvia Monoplacophora Conchifera is the subpylum of Mollusca comprising the shell bearing molluscs: Gastropoda, Scaphopoda, Rostroconchia, Cephalopoda, Bivalvia and Monoplacophora. ... Structure of the chitin molecule, showing two of the N-Acetylglucosamine units that repeat to form long chains in beta-1,4 linkage. ... Subclasses and families Subclass Chaetodermomorpha (Caudofoveata) Family Chaetodermidae Family Falcidentidae Family Limifossoridae Family Metachaetodermatidae Family Prochaetodermatidae Family Scutopidae Subclass Neomeniomorpha (Solenogastres) Family Acanthomeniidae Family Amphimeniidae Family Dondersiidae Family Drepanomeniidae Family Epimeniidae Family Gymnomeniidae Family Hemimeniidae Family Heteroherpiidae Family Imeroherpiidae Family Lepidomeniidae Family Macellomeniidae Family Meiomeniidae Family Neomeniidae Family Perimeniidae Family...

Research and classification

Wiwaxia's taxonomy, even which phylum it belongs to, remains a highly debated topic. Phylum (plural: phyla) is a taxon used in the scientific classification of life. ...

As an annelid

Charles Doolittle Walcott first described Wiwaxia in 1911, comparing it to modern polychaete worms. ^[1]. Classes and subclasses Class Polychaeta (paraphyletic?) Class Clitellata*    Oligochaeta - earthworms, etc. ... Charles Doolittle Walcott (March 31, 1850 - February 9, 1927) was an eminent American invertebrate paleontologist. ... Subclasses Palpata Scoleoida Tomopteris from plankton The Polychaeta or polychaetes are a class of annelid worms, generally marine. ...

Simon Conway Morris in 1985 agreed that there were similarities to polychaetes, but that Wiwaxia's sclerites did not seem to be homologous with the elytra (scales) of the annelids.^[2] Simon Conway Morris is a British paleontologist. ... Subclasses Palpata Scoleoida Tomopteris from plankton The Polychaeta or polychaetes are a class of annelid worms, generally marine. ... Sclerites are hardened body parts. ... Two or more structures are said to be homologous if they are alike because of shared ancestry. ... Elytra (sing: elytron) are modified, hardened forewings of certain insect orders, notably beetles (Coleoptera) and true bugs (Hemiptera). ...

Nick Butterfield, then a postgraduate paleontologist at Harvard inspired by Stephen Jay Gould's lectures, agreed that the sclerites were not like elytra, but on the contrary concluded that they resembled the chitinous bristles (chaetae) that project from the bodies of such modern annelids as bristleworms and earthworms. His conclusion, published in 1990, was that Wiwaxia was an annelid.^[3] In ^[1] he reiterated this conclusion, but noted that Wiwaxia does not appear to fit into the polychaetes, but appears rather to be a stem-group annelid. It has been suggested that Darwinian Fundamentalism be merged into this article or section. ... Structure of the chitin molecule, showing two of the N-Acetylglucosamine units that repeat to form long chains in beta-1,4 linkage. ... Chatae (singular cheta) are bristles or seta found on annelid worms such as the earthworm. ... Classes and subclasses Class Polychaeta (paraphyletic?) Class Clitellata*    Oligochaeta - earthworms, etc. ... Orders Amphinomida Capitellida Chaetopterida Cirratulida Cossurida Ctenodrillidae Eunicida Flabelligerida Magelonida Myzostomida Nerillida Opheliida Orbiniida Orweniida Phyllodocida Pisionidae Polygordiida Protodrilida Psammodrilidae Sabellida Spionida Spintheridae Sternaspida Terebellida The Polychaeta or Polychaetes are a class of annelid worms, generally marine, with a pair of fleshy protrusions on each body segment called parapodia that... Families   Acanthodrilidae   Ailoscolecidae   Alluroididae   Almidae   Biwadrilidae   Eudrilidae   Exxidae   Glossoscolecidae   Lumbricidae   Lutodrilidae   Megascolecidae   Microchaetidae   Ocnerodrilidae   Octochaetidae   Sparganophilidae Earthworm is the common name for the larger members of the Oligochaeta (which is either a class or subclass depending on the author) in the phylum Annelida. ... Subclasses Palpata Scoleoida Tomopteris from plankton The Polychaeta or polychaetes are a class of annelid worms, generally marine. ... Classes and subclasses Class Polychaeta (paraphyletic?) Class Clitellata*    Oligochaeta - earthworms, etc. ...

As a mollusk

Butterfield's view has more recently been challenged by the Danish zoologist Danny Eibye Jacobsen (2004) who, after detailed studies of all available material of Wiwaxia, argued that there are no characters clearly placing Wiwaxia with the polychaetes or annelids.^[4] Given that Wiwaxia has a creeping sole and what appears to be a radula, a placement with the mollusks therefore still seems most likely. For similar animals of as yet uncertain affinity, see Halkieria. Classes Caudofoveata Aplacophora Polyplacophora Monoplacophora Bivalvia Scaphopoda Gastropoda Cephalopoda † Rostroconchia The mollusks or molluscs are the large and diverse phylum Mollusca, which includes a variety of familiar creatures well-known for their decorative shells or as seafood. ... Subclasses Palpata Scoleoida Tomopteris from plankton The Polychaeta or polychaetes are a class of annelid worms, generally marine. ... Classes and subclasses Class Polychaeta (paraphyletic?) Class Clitellata*    Oligochaeta - earthworms, etc. ... Radula is the scientific name for the toothed chitinous ribbon in the mouth of gastropods. ... Halkieria evangelista from the Lower Cambrian Sirius Passet, North Greenland Halkieria is a fossil organism from the Lower to Middle Cambrian. ...

Relation to Halkieria

Wiwaxia is now considered to be related to the slug-like Halkieria due to the recently discovered Burgess shale organism, Orthozanclus reburrus. O. reburrus combines features of both Halkiera (scale mail sclerites and an anterior shell) and Wiwaxia (elongated, spine-like sclerites). Halkieria evangelista from the Lower Cambrian Sirius Passet, North Greenland Halkieria is a fossil organism from the Lower to Middle Cambrian. ... Slugs are gastropod mollusks without shells or with very small internal shells, in contrast to snails, which have a prominent coiled shell. ... Halkieria evangelista from the Lower Cambrian Sirius Passet, North Greenland Halkieria is a fossil organism from the Lower to Middle Cambrian. ...

References

• National Museum of Natural History (2005) Wiwaxia corrugata. Retrieved on Oct. 26, 2005.

1. ^ ^{a b} (2003) "Exceptional Fossil Preservation and the Cambrian Explosion". Integr. Comp. Biol. 43: 166-177. Retrieved on 2 Dec 2006. 
2. ^ Conway Morris, S. (1985). "The Middle Cambrian metazoan Wiwaxia corrugata (Matthew) from the Burgess Shale and Ogygopsis Shale, British Columbia, Canada". Phil. Trans. Roy. Soc. London 307: 507-586. 
3. ^ Butterfield, N. J. (1990). "A reassessment of the enigmatic Burgess Shale fossil Wiwaxia corrugata (Matthew) and its relationship to the polychaete Canadia spinosa. Walcott". Paleobiology 16: 287-303. 
4. ^ Eibye-Jacobsen D (SEP 2004). "A reevaluation of Wiwaxia and the polychaetes of the Burgess Shale". LETHAIA 37 (3): 317-335. 

External Links

• Pharyngula entry on Orthozanclus reburrus