Geodiversitas | |
A new archaic homodont toothed cetacean (Mammalia, Cetacea, Odontoceti) from the early Miocene of Peru | |
Olivier Lambert1  Giovanni Bianucci1  Christian De Muizon1  | |
关键词: Cetacea; Odontoceti; homodont; Early Miocene; Peru; phylogeny; new genus; new species; Cetacea; Odontoceti; homodonte; Miocène inférieur; Pérou; phylogénie; genre nouveau; espèce nouvelle; | |
DOI : 10.5252/g2015n1a4 | |
学科分类:生物科学(综合) | |
来源: Museum National d Histoire Naturelle | |
【 摘 要 】
Apartfromafewexceptions,extantodontocetes(toothedcetaceans)exhibitaroughlyhomodontdentition.Thetransitionfrombasilosaurid-likedouble-rootedcheekteethwithaccessorydenticlestosingle-rootedconicalteethoccurredduringthelateOligocene-earlyMiocene.Atthattime,severalcladesofnowextinct,homodontandpredominantlylong-snoutedodontocetesappearedinthefossilrecord.Amongthem,membersofthegeneraArgyrocetusLydekker,1893andMacrodelphinusWilson,1935,fromtheearlyMioceneoftheNortheastPacificandArgentina,weretentativelyattributedtothefamilyEurhinodelphinidae.However,duetothefragmentarystateofthespecimens,unambiguousapomorphiesofthefamilycouldnotbedetected.Basedontwowell-preservedskullswithassociatedmandibularelements,discoveredinearlyMiocenelayersoftheChilcatayFormation(PiscoBasin,Peru),wereportonanewgenusandspeciesoflong-snoutedhomodontodontocete,Chilcacetuscavirhinusn.gen.,n.sp.Characterizedby,amongothers,thepresenceofalveoliontheanteriorpremaxillaryportionoftherostrum,thelackofalateralgrooveontherostrum,anterodorsallyelevatednasals,apossiblyautapomorphiccavitybetweennasalsandmesethmoidintheposteriorwallofthebonynares,ahightemporalfossa,andtheabsenceofankylosisalongthemandibularsymphysis,C.cavirhinusn.gen.,n.sp.doesnotfitinanyoftheknownodontocetefamilies,butsharesseveralmorphologicalfeatureswithArgyrocetusspp.andMacrodelphinus.Ourphylogeneticanalysis,basedon77charactersfor35odontocetetaxa,suggeststheexistenceofanearlyMioceneEasternPacificlong-snoutedhomodontodontoceteclade(withanhypotheticalSouthAtlanticmember,thepoorlyknownArgyrocetuspatagonicusLydekker,1893),distinctfromtheonlysuperficiallysimilareoplatanistidsandeurhinodelphinids.Furthermore,ourconsensustreeindicatesanearlybranchingofthisnewcladecomparedtootherhomodontodontocetelineages.Unfortunately,theresultsofthecladisticanalysispresentedherearenotwellsupported;areappraisalofArgyrocetusandMacrodelphinusisneededtomoreclearlydefinethenewcladeandbolsteritsphylogenticposition.
【 授权许可】
Unknown
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