Obolellata

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Obolellata
Temporal range: Lower Cambrian – Middle Cambrian
Scientific classification e
Kingdom: Animalia
Phylum: Brachiopoda
Class: †Obolellata
Order: †Obolellida
Orders & families
  • Obolellida Rowell, 1965
    • Trematobolidae
      • (incomplete list)
  • Naukatida Popov and Tikonov 1990
    • Streng et al 2016[1]
      • (incomplete list)

The Obolellata are a class of Rhynchonelliform brachiopods with two orders, Obolellida and Naukatida. They are essentially restricted to the lower-middle Cambrian.[1]

Obolellida[]

Obolellida is a small, extinct order of brachiopods that existed from the early to middle Cambrian period. The relationship of the Obolellida with other inarticulates is unclear, and were previously grouped together with the , before being given their own order.

One representative, , has been linked to the origin of calcitic shelled brachiopods more generally, hinting that obolellids may be paraphyletic.[2]

Trematobolidae includes taxa such as Alisina, whose soft-part anatomy is partly known.

Anatomy[]

The shell is typically , , and oval or subcircular in shape. They are like other inarticulates in that, as with the lingulids, the shell has no hinge, at least in the earliest examples.[3] It is thought they may have used a hydraulic mechanism. However they later seem to develop a primitive articulation, in which some used a levator mechanism for opening the shell.[4] At the posterior is a ventral valve with a defined flat-shelf. The pedicle opening can be positioned at various positions.[5]

Naukatida[]

Some of these are coral-like creatures.[1]

References[]

Key reference: Popov, Leonid E.; Holmer, Lars E. (2000). "Class Obolellata". Treatise on Invertebrate Paleontology. Vol. Part H Brachiopoda. University of Kansas Press. pp. 200–215. ISBN 0-8137-3108-9.

  1. ^ a b c Streng, M., A. D. Butler, J. S. Peel, R. J. Garwood, and J.-B. Caron. 2016. A new family of Cambrian rhynchonelliformean brachiopods (Order Naukatida) with an aberrant coral-like morphology. Palaeontology, 59:269–293.
  2. ^ Balthasar, U. (2008). ~Mummpikia~ gen. nov. and the origin of calcitic-shelled brachiopods. Palaeontology 51, 263–279.
  3. ^ "Paleos, Order Obolellida". Archived from the original on 2006-09-20. Retrieved 2006-07-04.
  4. ^ Lipps, Jere H.; Signor, Philip W. (January 1, 1992). Origin and Early Evolution of the Metazoa. Springer. ISBN 0-306-44067-9. Page 417.
  5. ^ "McGraw-Hill AccessScience, Obolellida". Archived from the original on 2007-03-12. Retrieved 2006-07-04.
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