| Microconchida Temporal range:
| |
|---|---|
| |
| Palaeoconchus angulatus (Hall, 1861) on a brachiopod from the Middle Devonian (Givetian) of Michigan | |
Scientific classification 
| |
| Kingdom: | Animalia |
| Class: | โ Tentaculita |
| Order: | โ Microconchida Weedon 1991 |
| Genera | |
The order Microconchida is a group of small, spirally-coiled, encrusting fossil "worm" tubes from the class Tentaculita found from the Upper Ordovician to the Middle Jurassic (Bathonian) around the world.[1][2][3][4][5] They have lamellar calcitic shells, usually with pseudopunctae or punctae and a bulb-like origin. Many were long misidentified as the polychaete annelid Spirorbis until studies of shell microstructure and formation showed significant differences.[6] All pre-Cretaceous "Spirorbis" fossils are now known to be microconchids.[6] Their classification at the phylum level is still debated. Most likely they are some form of lophophorate, a group which includes phoronids, bryozoans and brachiopods. Microconchids may be closely related to the other encrusting tentaculitoid tubeworms, such as Anticalyptraea, trypanoporids and cornulitids.[3] Their habitat is more controversial. While there is a consensus that they were present in the seas and in brackish water, there is a debate about their presence in freshwater. Some studies suggested that they colonised freshwater in the Early Devonian,[7][8] whereas others suggest that microconchids never colonised that environment.[9][10] A recent review of the associated fauna failed to find reliable occurrences of microconchids in the Middle Devonian to Early Permian time interval because microconchids seem to co-occur with other signs of marine influence,[11] such as xiphosurans and chondrichthyan egg capsules.[12]
References
edit- ^ Weedon, M.J. 1991. "Microstructure and affinity of the enigmatic Devonian tubular fossil Trypanopora". Lethaia 24:227-234 doi:10.1111/j.1502-3931.1991.tb01471.x.
- ^ Vinn, O. 2006. "Two new microconchid (Tentaculita Bouฤek 1964) genera from the Early Palaeozoic of Baltoscandia and England". Neues Jahrbuch fรผr Geologie und Palรคontologie 2006:89-100.
- ^ a b Vinn, O. 2010. "Adaptive strategies in the evolution of encrusting tentaculitoid tubeworms". Palaeogeography, Palaeoclimatology, Palaeoecology 292:211โ221.
- ^ Vinn, O. & Mutvei, H. 2009. "Calcareous tubeworms of the Phanerozoic". Estonian Journal of Earth Sciences 58:286-296.
- ^ Zaton, M. & Vinn, O. 2011. "Microconchids and the rise of modern encrusting communities". Lethaia 44:5-7 doi:10.1111/j.1502-3931.2010.00258.x
- ^ a b Taylor, P.D. & Vinn, O. 2006. "Convergent morphology in small spiral worm tubes ("Spirorbis") and its palaeoenvironmental implications". Journal of the Geological Society, London 163:225-228 doi:10.1144/0016-764905-145.
- ^ Zatoล, Michaล; Vinn, Olev; Tomescu, Alexandru M. F. (1 November 2012). "Invasion of freshwater and variable marginal marine habitats by microconchid tubeworms โ an evolutionary perspective". Geobios. 45 (6): 603โ610. doi:10.1016/j.geobios.2011.12.003. ISSNย 0016-6995.
- ^ Zatoล, Michaล; Wilson, Mark A.; Vinn, Olev (1 January 2016). "Comment on the paper of Gierlowski-Kordesch and Cassle "The 'Spirorbis' problem revisited: Sedimentology and biology of microconchids in marineโnonmarine transitions" [Earth-Science Reviews, 148 (2015): 209โ227]". Earth-Science Reviews. 152: 198โ200. doi:10.1016/j.earscirev.2015.11.012. ISSNย 0012-8252.
- ^ Gierlowski-Kordesch, Elizabeth H.; Cassle, Christopher F. (1 September 2015). "The 'Spirorbis' problem revisited: Sedimentology and biology of microconchids in marine-nonmarine transitions". Earth-Science Reviews. 148: 209โ227. doi:10.1016/j.earscirev.2015.04.010. ISSNย 0012-8252.
- ^ Gierlowski-Kordesch, Elizabeth H.; Falcon-Lang, Howard J.; Cassle, Christopher F. (1 January 2016). "Reply to comment on the paper of Gierlowski-Kordesch and Cassle "The 'Spirorbis' problem revisited: Sedimentology and biology of microconchids in marineโnonmarine transitions"". Earth-Science Reviews. 152: 201โ204. doi:10.1016/j.earscirev.2015.11.011. ISSNย 0012-8252.
- ^ Laurin, Michel (30 December 2024). "Habitat of early stegocephalians (Chordata, Vertebrata, Sarcopterygii): a little saltier than most paleontologists like?". Fossil Record. 27 (3): 299โ332. doi:10.3897/fr.27.123291. ISSNย 2193-0074.
- ^ Lomax, Dean R.; Robinson, Peter; Cleal, Christopher J.; Bowden, Alistair; Larkin, Nigel R. (2016). "Exceptional preservation of Upper Carboniferous (lower Westphalian) fossils from Edlington, Doncaster, South Yorkshire, UK". Geological Journal. 51 (1): 42โ50. doi:10.1002/gj.2602. ISSNย 1099-1034.
- Wilson, M.A., Yancey, T.E. and Vinn, O. 2011. "A new microconchid tubeworm from the Lower Permian (Artinskian) of central Texas, USA". Acta Palaeontologica Polonica 56:785-791 doi:10.4202/app.2010.0086.
- Zaton, M., Wilson, M.A. and Vinn, O. 2012. "Redescription and neotype designation of the Middle Devonian microconchid (Tentaculita) species โSpirorbisโ angulatus Hall, 1861". Journal of Paleontology 86:417-424 doi:10.1666/11-115.1.
