Microconchida

{{Short description|Extinct order of molluscs}} {{Automatic taxobox | fossil_range = {{fossil range|Upper Ordovician|Bathonian|Upper Ordovician - Middle Jurassic |refs=(Taylor and Vinn, 2006)}} | image = MicroconchidDevonianPotterFarm082111.jpg | image_caption = ''Palaeoconchus angulatus'' (Hall, 1861) on a brachiopod from the Middle Devonian (Givetian) of Michigan | taxon = Microconchida | authority = Weedon 1991 | subdivision_ranks = Genera | subdivision = *''Annuliconchus'' *''Helicoconchus'' *''Microconchus'' *''Palaeoconchus'' *''Polonoconchus'' *''Punctaconchus'' }} thumb|''Helicoconchus elongatus'', a microconchid from the Lower Permian of Texas. (See Wilson et al., 2011).

thumb|''Punctaconchus midfordensis'' (Richardson, 1907). Bajocian, Clypeus Grit Member, Worgan's Quarry, Gloucestershire, UK. {{Portal|Paleontology}}

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.<ref name="Weedon91" /><ref name="Vinn2006" /><ref name="Vinn2010" /><ref name="VinnMutvei2009" /><ref name="ZatonVinn2011" /> 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.<ref name="TaylorVinn" /> All pre-Cretaceous "''Spirorbis''" fossils are now known to be microconchids.<ref name="TaylorVinn" /> 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.<ref name="Vinn2010" /> 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,<ref name="Zatoń et al. 2012">{{cite journal |last1=Zatoń |first1=Michał |last2=Vinn |first2=Olev |last3=Tomescu |first3=Alexandru M. F. |title=Invasion of freshwater and variable marginal marine habitats by microconchid tubeworms – an evolutionary perspective |journal=Geobios |date=1 November 2012 |volume=45 |issue=6 |pages=603–610 |doi=10.1016/j.geobios.2011.12.003 |url=https://doi.org/10.1016/j.geobios.2011.12.003 |issn=0016-6995|url-access=subscription }}</ref><ref name="Zatoń et al. 2016">{{cite journal |last1=Zatoń |first1=Michał |last2=Wilson |first2=Mark A. |last3=Vinn |first3=Olev |title=Comment on the paper of Gierlowski-Kordesch and Cassle “The ‘Spirorbis’ problem revisited: Sedimentology and biology of microconchids in marine–nonmarine transitions” [Earth-Science Reviews, 148 (2015): 209–227] |journal=Earth-Science Reviews |date=1 January 2016 |volume=152 |pages=198–200 |doi=10.1016/j.earscirev.2015.11.012 |url=https://doi.org/10.1016/j.earscirev.2015.11.012 |issn=0012-8252|url-access=subscription }}</ref> whereas others suggest that microconchids never colonised that environment.<ref name="Gierlowski-Kordesch & Cassle 2015">{{cite journal |last1=Gierlowski-Kordesch |first1=Elizabeth H. |last2=Cassle |first2=Christopher F. |title=The ‘Spirorbis’ problem revisited: Sedimentology and biology of microconchids in marine-nonmarine transitions |journal=Earth-Science Reviews |date=1 September 2015 |volume=148 |pages=209–227 |doi=10.1016/j.earscirev.2015.04.010 |url=https://doi.org/10.1016/j.earscirev.2015.04.010 |issn=0012-8252|url-access=subscription }}</ref><ref name="Gierlowski-Kordesch et al. 2016">{{cite journal |last1=Gierlowski-Kordesch |first1=Elizabeth H. |last2=Falcon-Lang |first2=Howard J. |last3=Cassle |first3=Christopher F. |title=Reply to comment on the paper of Gierlowski-Kordesch and Cassle “The ‘Spirorbis’ problem revisited: Sedimentology and biology of microconchids in marine–nonmarine transitions” |journal=Earth-Science Reviews |date=1 January 2016 |volume=152 |pages=201–204 |doi=10.1016/j.earscirev.2015.11.011 |url=http://dx.doi.org/10.1016/j.earscirev.2015.11.011 |issn=0012-8252|url-access=subscription }}</ref> 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,<ref name="Laurin 2024">{{Cite journal |last=Laurin |first=Michel |date=30 December 2024 |title=Habitat of early stegocephalians (Chordata, Vertebrata, Sarcopterygii): a little saltier than most paleontologists like? |url=https://doi.org/10.3897/fr.27.123291 |journal=Fossil Record |volume=27 |issue=3 |pages=299–332 |doi=10.3897/fr.27.123291 |issn=2193-0074 |doi-access=free}}</ref> such as xiphosurans and chondrichthyan egg capsules.<ref name="Lomax et al. 2016">{{cite journal |last1=Lomax |first1=Dean R. |last2=Robinson |first2=Peter |last3=Cleal |first3=Christopher J. |last4=Bowden |first4=Alistair |last5=Larkin |first5=Nigel R. |title=Exceptional preservation of Upper Carboniferous (lower Westphalian) fossils from Edlington, Doncaster, South Yorkshire, UK |journal=Geological Journal |date=2016 |volume=51 |issue=1 |pages=42–50 |doi=10.1002/gj.2602 |url=https://doi.org/10.1002/gj.2602 |language=en |issn=1099-1034|url-access=subscription }}</ref>

==References== {{Reflist|refs= <ref name="TaylorVinn">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}}.</ref> <ref name="Weedon91">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}}.</ref> <ref name="Vinn2006">Vinn, O. 2006. "Two new microconchid (Tentaculita Bouček 1964) genera from the Early Palaeozoic of Baltoscandia and England". ''Neues Jahrbuch für Geologie und Paläontologie'' 2006:89-100.</ref> <ref name="Vinn2010">Vinn, O. 2010. "Adaptive strategies in the evolution of encrusting tentaculitoid tubeworms". ''Palaeogeography, Palaeoclimatology, Palaeoecology'' 292:211–221.</ref> <ref name="VinnMutvei2009">Vinn, O. & Mutvei, H. 2009. "[https://kirj.ee/public/Estonian_Journal_of_Earth_Sciences/2009/issue_4/earth-2009-4-286-296.pdf Calcareous tubeworms of the Phanerozoic]". ''Estonian Journal of Earth Sciences'' 58:286-296.</ref> <ref name="ZatonVinn2011">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}}</ref> }} * 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 ''‘Spirorbis’ angulatus'' Hall, 1861". ''Journal of Paleontology'' 86:417-424 {{doi|10.1666/11-115.1}}.

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Category:Tentaculita Category:Late Ordovician first appearances Category:Middle Jurassic extinctions Category:Prehistoric animal orders