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Vetulicolia

Vetulicolia is an extinct phylum erected by Shu et al. (2001), encompassing several early-Cambrian fossil forms. They suggest that these animals were early deuterostomes. The bodyplan consists of two parts, a voluminous anterior section with a large "mouth" and a row of five round to oval-shaped features on each side that are interpreted as gills (or at least openings in the vicinity of the pharynx) and a posterior section with seven segments. The area where the anterior and posterior parts join is constricted. The phylum Vetulicolia is defined by Shu et al. to include the family Didazoonidae, with the genera Didazoon and Xidazoon, the family Vetulicolidae, with the genera Pomatrum and Vetulicola, and the genus Banffia. The authors also propose that vetulicolians and yunnanozoans may be closely related.

Shu (2003) has argued that the vetulicolians probably represent an early specialized side-branch of deuterostomes, and that this implies that segmentation in cephalochordates and vertebrates may be derived from the common ancestor of protostomes and deuterostomes. Briggs et al. (2005) described Skeemella from the Middle Cambrian of Utah as having affinity to Vetulicolia, but also as having arthropod features, thus confounding assignment of Vetulicolia to Deuterostomia. Dominguez and Jefferies have argued, based on morphological analysis, that Vetulicola (and by implication, other Vetulicolians) is a urochordate, and probably a stem-group larvacean. The taxonomic placement of the Vetulicolians remains controversial.

Classification

• Phylum Vetulicolia
  • Class Vetulicolia
    • Order Vetulicolida
      • Family Vetulicolidae
        • Genus Vetulicola
          • Vetulicola rectangulata
          • Vetulicola cuneata
          • Vetulicola gangtoucunensis
        • Genus Banffia
          • Banffia constricta
          • Banffia confusa
      • Family Didazoonidae
        • Genus Didazoon
          • Didazoon haoae
        • Genus Xidazoon
          • Xidazoon stephanus
    • ?Order Yunnanozoa
      • Family Yunnanozoonidae
        • Genus Yunnanozoon
          • Yunnanozoon lividum
        • Genus Haikouella
          • Haikouella lanceolata

References

• Shu, D.-G., Conway Morris, S., Han, J., Chen, L., Zhang, X.-L., Zhang, Z.-F., Liu, H.-Q., Li, Y., and Liu, J.-N. 2001. Primitive Deuterostomes from the Chengjiang Lagerstätte (Lower Cambrian, China), Nature, 414:419-424. (November 11, 2001). [1].
• Briggs, D., Lieberman, B., Halgedahl, S. and Jarrard, R. (2005), A new metazoan from the Middle Cambrian of Utah and the nature of Vetulicolia. Palaeontology 48: 681-686.
• Shu, Degan. 2003. A paleontological perspective of vertebrate origin. Chinese Science Bulletin, Vol. 48 No. 8 725-735. April, 2003. [2] - URL retrieved June 22, 2006
• Dominguez, Patricio and Jeffries, Richard. (2003). Fossil evidence on the origin of appendicularians. Paper read at International Urochordate Meeting 2003. Abstract at [3] - URL retrieved June 22, 2006

External links

• New phylum on the block - Accessed January 3, 2008
• Once We Were Worms
• Photos and drawings of fossils of various Vetulicolians - Accessed January 3, 2008