Editing Polychaete (section)

==Fossil record==
[[Crown group#Stem groups|Stem-group]] polychaete fossils are known from the [[Sirius Passet]] [[Lagerstätte]], a rich, sedimentary deposit in Greenland tentatively dated to the late [[Atdabanian]] (early [[Cambrian]]). The oldest found is ''[[Phragmochaeta canicularis]]''.<ref>{{Cite journal | last1 = Conway Morris | first1 = S. | last2 = Peel | first2 = J. S. | title = The Earliest Annelids: Lower Cambrian Polychaetes from the Sirius Passet Lagerstätte, Peary Land, North Greenland | journal = Acta Palaeontologica Polonica | volume = 53 | pages = 137–148 | year = 2008 | doi = 10.4202/app.2008.0110 | doi-access = free }}</ref> Many of the more famous [[Burgess Shale]] organisms, such as ''[[Canadia (annelid)|Canadia]]'', may also have polychaete affinities. ''[[Wiwaxia]]'', long interpreted as an annelid,<ref name="JSTORExpressionerror">{{Cite journal| last1 = Butterfield | first1 = N. J.| title = A reassessment of the enigmatic Burgess Shale fossil ''Wiwaxia corrugata'' (Matthew) and its relationship to the polychaete ''Canadia spinosa'' Walcott| jstor = 2400789| journal = Paleobiology| volume = 16| issue = 3| pages = 287–303| year = 1990 |doi=10.1017/S0094837300010009 | bibcode = 1990Pbio...16..287B| s2cid = 88100863}}</ref> is now considered to represent a mollusc.<ref name="Smith2012">{{cite journal | last = Smith | first = M. R. | year = 2012 | title = Mouthparts of the Burgess Shale fossils ''Odontogriphus ''and ''Wiwaxia'': Implications for the ancestral molluscan radula | journal = Proceedings of the Royal Society B | volume = 279| issue = 1745| pages = 4287–4295 | doi = 10.1098/rspb.2012.1577 | pmid = 22915671 | pmc = 3441091}}</ref><ref name="Smithin press">{{cite journal | last1 = Smith | first1 = M. R. | year = 2014 | title = Ontogeny, morphology and taxonomy of the soft-bodied Cambrian 'mollusc' ''Wiwaxia'' | journal = Palaeontology | volume = 57 | issue = 1 | pages =  215–229 | doi = 10.1111/pala.12063| bibcode = 2014Palgy..57..215S | s2cid = 84616434 | doi-access = free }}</ref> An even older fossil, ''[[Cloudina]]'', dates to the terminal [[Ediacaran]] period; this has been interpreted as an early polychaete, although consensus is absent.<ref name=Miller>{{Cite book
 | author = Miller, A. J.
 | year = 2004
 | title = A revised morphology of ''Cloudina'' with ecological and phylogenetic implications
 | citeseerx = 10.1.1.526.5035
 }}</ref><ref name=VinnZaton>{{cite journal |last1=Vinn |first1=Olev |last2=Zatoń |first2=Michał |title=Inconsistencies in proposed annelid affinities of early biomineralized organism ''Cloudina'' (Ediacaran): structural and ontogenetic evidences |journal= Carnets de Géologie |date=March 2012 |issue=Lettres |doi=10.4267/2042/46095 |doi-access=free }}</ref>

Being [[soft-bodied organisms]], the fossil record of polychaetes is dominated by their fossilized jaws, known as [[scolecodont]]s, and the [[mineral]]ized tubes that some of them secrete.<ref name="VinnMutvei2009tubeworms">{{cite journal |last1=Vinn |first1=O |last2=Mutvei |first2=H |title=Calcareous tubeworms of the Phanerozoic |journal=Estonian Journal of Earth Sciences |date=2009 |volume=58 |issue=4 |pages=286 |doi=10.3176/earth.2009.4.07 |doi-access=free }}</ref> Most important [[biomineralising polychaetes]] are [[Serpulidae|serpulids]], [[Sabellidae|sabellids]], and [[Cirratulidae|cirratulids]]. Polychaete cuticle does have some [[preservation potential]]; it tends to survive for at least 30 days after a polychaete's death.<ref name="Briggs1993"/> Although biomineralisation is usually necessary to preserve soft tissue after this time, the presence of polychaete muscle in the nonmineralised Burgess shale shows this need not always be the case.<ref name=Briggs1993/> Their preservation potential is similar to that of [[jellyfish]].<ref name="Briggs1993"/>