A re-examination of Lupopsyrus pygmaeus Bernacsek & Dineley, 1977 (Pisces, Acanthodii)

[摘要] NewanatomicaldetailsaredescribedfortheacanthodianLupopsyruspygmaeusBernacsekamp;Dineley,1977,basedonnewlyprepared,nearlycompletebodyfossilsfromtheMOTHlocality,NorthwestTerritories,Canada.Newinterpretationsofpreviouslyknownstructuresareprovided,whilethehead,tail,andsensorylinesofL.pygmaeusaredescribedforthefirsttime.ThepectoralgirdleofL.pygmaeusshowsnoevidenceofpinnalandloricalplatesasmentionedintheoriginalspeciesdescription.Instead,thedermalelementsofthepectoralregionappeartocompriseasinglepairofprepectoralspineswhichrestontransverselyorientedprocoracoids,andlarge,shallowlyinserted,ornamentedpectoralfinspineswhichcontactboththeprocoracoidsandscapulocoracoids.ThescalesofL.pygmaeuslackgrowthzonesandmineralizedbasaltissue,andsuperficiallyresemblescalesofthelodontsormonodontodeplacoidscalesofearlychondrichthyans,andnotthetypicalscalesofacanthodians.However,L.pygmaeuspossessesperichondrally-ossifiedpork-chopshapedscapulocoracoids,aseriesofhyoideangillplates,andscalegrowththatoriginatesnearthecaudalpeduncle;thesefeaturessuggestarelationshiptoacanthodians.Priortothisstudy,bothauthorsconductedseparatecladisticanalyseswhichresultedindifferingtreepositionsforL.pygmaeusanditsrelationshipswithintheAcanthodii.However,bothanalysesdidagreethatthereisnoevidenceallyingL.pygmaeustothetraditional“climatiid”acanthodianscontrarytoprevioushistoricalclassifications.

[学科分类] 生物科学（综合）

[关键词] Climatiiformes;Lower Devonian;Lochkovian;gnathostome;systematics;Climatiiformes;Dévonien inférieur;Lochkovien;gnathostome;systématique