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 is a small, extinct order of inarticulate 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 Siphonotretacea, before being given their own order.
One representative, Mummpikia, 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.
Anatomyedit
The shell is typically impunctate, biconvex, 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]
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. ISBN0-8137-3108-9.
^ abcStreng, 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.
^Balthasar, U. (2008). ~Mummpikia~ gen. nov. and the origin of calcitic-shelled brachiopods. Palaeontology 51, 263–279.
^. Archived from the original on 2006-09-20. Retrieved 2006-07-04.
^Lipps, Jere H.; Signor, Philip W. (January 1, 1992). Origin and Early Evolution of the Metazoa. Springer. ISBN0-306-44067-9. Page 417.
^. Archived from the original on 2007-03-12. Retrieved 2006-07-04.
April 14, 2024
obolellata, class, rhynchonelliform, brachiopods, with, orders, obolellida, naukatida, they, essentially, restricted, lower, middle, cambrian, temporal, range, lower, cambrian, middle, cambrian, preꞒ, nscientific, classificationdomain, eukaryotakingdom, animal. The Obolellata are a class of Rhynchonelliform brachiopods with two orders Obolellida and Naukatida They are essentially restricted to the lower middle Cambrian 1 ObolellataTemporal range Lower Cambrian Middle Cambrian PreꞒ Ꞓ O S D C P T J K Pg NScientific classificationDomain EukaryotaKingdom AnimaliaPhylum BrachiopodaSubphylum RhynchonelliformeaClass ObolellataOrders amp familiesObolellida Rowell 1965ObolellidaeTrematobolidae incomplete list Naukatida Popov and Tikonov 1990Tomteluvidae Streng et al 2016 1 incomplete list Contents 1 Obolellida 1 1 Anatomy 2 Naukatida 3 ReferencesObolellida editObolellida is a small extinct order of inarticulate 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 Siphonotretacea before being given their own order One representative Mummpikia 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 edit The shell is typically impunctate biconvex 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 editSome of these are coral like creatures 1 References editKey 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 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 Balthasar U 2008 Mummpikia gen nov and the origin of calcitic shelled brachiopods Palaeontology 51 263 279 Paleos Order Obolellida Archived from the original on 2006 09 20 Retrieved 2006 07 04 Lipps Jere H Signor Philip W January 1 1992 Origin and Early Evolution of the Metazoa Springer ISBN 0 306 44067 9 Page 417 McGraw Hill AccessScience Obolellida Archived from the original on 2007 03 12 Retrieved 2006 07 04 Retrieved from https en wikipedia org w index php title Obolellata amp oldid 1078120324, wikipedia, wiki, book, books, library,
