Machaeracanthus goujeti n. sp. (Acanthodii) from the Lower Devonian of Spain and northwest France, with special reference to spine histology

Geodiversitas

Carlos Martínez-Pérez¹  Rodrigo Soler-Gijón¹  Héctor Botella¹ 

关键词: Machaeracanthus;    Acanthodii fin spines;    Lochkovian-Pragian;    Celtiberia;    Spain;    new species;    Machaeracanthus;    Aiguillons pectoraux;    Acanthodiens;    Lochkovien-Praeuien;    Celtiberie;    Espagne;    espèce nouvelle;   

DOI  :  10.5252/g2012n4a3

学科分类：生物科学（综合）

来源: Museum National d Histoire Naturelle

【 摘 要 】

Wedescribehereanewmachaeracanthidacanthodian(Machaeracanthusgoujetin.sp.),basedonisolatedspines,scalesandscapulocoracoidsfromtheLowerDevonian(Lochkovian-Pragian)oftheNoguerasFormation,Celtiberia,Spain.ThenewtaxonalsoincludesafragmentaryspineandisolatedscalesfromtheLowerDevonianofnorthernSpain(PalenciaandCantabrianMountains)andwesternFrance(Saint-Céneré)originallyassignedtoMachaeracanthussp.ThespinesofM.goujetin.sp.comprisetwomorphotypesinagreementwiththemorphofunctionalmodelofapairofpectoralspinesarticulatingwiththepectoralgirdlealreadyindicatedforM.hunsrueckianumSüdkampamp;Burrow,2007,M.longaevusEastman,1907,andM.sulcatusNewberry,1857.ThemorphologyandsizeofthespinesdistinguishM.goujetin.sp.fromthecoevalspeciesM.bohemicusBarrande,1872;thenewspeciesmostcloselyresemblestheyoungerspeciesM.peracutusNewberry,1857.ThespinesofM.goujetin.sp.consistoftrabecularandlamellardentinelayerswhichformthewallofthecentralaxis(piercedbyalongitudinalpulpcavity)andlateralexpansions.Themostsuperficiallayerofdentineiscentrifugallydepositedinthecompletespine;thisconditionisfoundinfinspinesofsomechondrichthyansandcontrastswiththatobservedintypicalacanthodianfinspineswheretheexsertedportionisornamentedwithribsofcentripetallygrowingdentine.VerysmallspinesandscapulocoracoidsofM.goujetin.sp.describedhere,arethefirstreportofjuvenilespecimensofaspeciesofMachaeracanthusNewberry,1857.Thedistalpartofthejuvenilespinelackslateralexpansions(keelandwing)anddemonstratesthefirststageinthedevelopmentofthespine.

【 授权许可】

Unknown