Mongolitubulus

Mongolitubulus
Mongolitubulus
Temporal range: Lower Cambrian–Early Middle Cambrian[1]
Scientific classification e
Kingdom: Animalia
Phylum: Arthropoda
stem group: Crustacea
Order: Bradoriida
Genus: Mongolitubulus
Missarzhevsky, 1977
Species
  • M. henrikseni Skovsted & Peel, 2001
  • M. squamifer Missarzhevsky, 1977 (type)
Synonyms
  • Rushtonites Hinz 1987

Mongolitubulus is a genus of small shelly fossil. It is potentially a synonym with Rushtonites, and owing to the similarity of the two genera[1] they are both dealt with herein.

Contents

Morphology

The fossils consist of round, slender, pointed, spines with a slight curvature, and are covered with short triangular processes.[1] Spines very from sub-millimetric up to two centimetres in length, but do not show any growth lines, suggesting that they were moulted and replaced.[2] Species are defined on the basis of the ornamentation, which may of course be convergent.

Affinity

M. henrikseni has been shown to be part of the carapace of a bivalved bradoriid arthropod.[3] However, the affinity of M. squamifer is still unresolved; the genus may transpire to be a form taxon, which would require M. henrikseni to be re-classified into a new genus.[3] Unlike the spines of M. henrikseni, which flare out at the base where they attach to the cuticle, the spines of M. squamifer are more parallel-sided, with the fossil material becoming thinner towards the base: consistent with their attachment to non-mineralized cuticle.[2] M. squamifer spines appear to have formed in pairs, owing to their symmetry; on this basis they have been likened to the spines of certain armoured lobopods known from Burgess shale-type deposits.[2]

Preservation

The spines often comprise layers of phosphate, with a central void often infilled with diagenetic phosphate.[2] Similar spines have been recovered from acid macerations, where they are preserved as films of organic carbon.[4]

Distribution

The fossils are known from the Botomian to the lower strata of the Middle Cambrian,[1] and have a worldwide distribution.[2]

References

  1. ^ a b c d Skovsted, C. E.; Peel, J. S. (2001). http://2dgf.dk/xpdf/bull48-2-135-147.pdf. 
  2. ^ a b c d e Dzik, J. (2003). "Early Cambrian lobopodian sclerites and associated fossils from Kazakhstan". Palaeontology 46: 93. doi:10.1111/1475-4983.00289. http://www.paleo.pan.pl/people/Dzik/Publications/Mongolitubulus.pdf.  edit
  3. ^ a b Skovsted, C. (2005). "A carapace of the bradoriid arthropod Mongolitubulus from the Early Cambrian of Greenland". GFF 127: 217. doi:10.1080/11035890501273217.  edit
  4. ^ Butterfield, N. J.; Nicholas, C. J. (1996). "Burgess Shale-Type Preservation of Both Non-Mineralizing and 'Shelly' Cambrian Organisms from the Mackenzie Mountains, Northwestern Canada". Journal of Paleontology 70 (6): 893–899. JSTOR 1306492.  edit

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