Bulletin of geosciences | |
The alleged astragalar remains of Didolodus Ameghino, 1897 (Mammalia, Panameriungulata) and a critic of isolated bone association models | |
Gelfo JN1  Lorente M1  | |
关键词: South America; Paleogene; Didolodontidae; astragali; regression equation models; | |
DOI : | |
来源: Czech Geological Survey | |
【 摘 要 】
PostcranialcharactersofSouthAmericannativeungulatesareimportantinordertoanalyzetheirrelationshipsintheactualtheriantaxonomy,particularlytotesttheirallegedafrotherianaffinities.Inthissense,themostprimitiveandoldestSouthAmericaneutheriansarerepresentedbytwoendemicgroupsof“condylarthsâ€,theKollpaniinaeandDidolodontidae.Theseforms,characterizedbylowercrownedbunodontdentition,haveneverbeenfoundindirectassociationwiththeirpostcranialremains.Eventhough,severalskeletalelementshavebeenassignedtosomeofforms,followingdifferentassumptionsandcriteria.Twodistinctastragalarremains(MACN-CA10737andAMNH117457)havebeenreferredtothegenusDidolodus,oneofthemostcommondidolodontidsfromearlyandmiddleEocenePatagonianoutcrops.Herewedescribeindetailandillustratethesematerials.Acriticalanalysisismadeofseveralregressionequationmodelswhichhavebeenusedinothercasestoassociatebysizeisolatedpostcranialelementstotaxadefinedbyteeth.Anewmodelwasformulatedbasedon19modernbunodontmammalswithdirectlyassociatedskeletonsinordertotesttheaccuracyoftheregressionequations.AlthoughtheresultsoftheequationmodelsfailedtoaccuratlyassignedtheisolatedastragalitoanyoftheDidolodusspecies,theycanbeusedasagoodtooltodisprovetheassociationhypothesis.AbroadcomparisonwithastragalarremainsofSouthAmericannativeungulatesindicatesthatMACN-CA10737hasnotoungulateaffinities,incontrastAMNH117457resemblestheastragaliassignedtodidolodontidsfromSaoJosédeItaboraÃ,Brazil,accordingtothemodelscriticizedhere.Thesimilitudeisparticularlyduetothebroaddevelopmentofthecotylarfossa,acharacterproposedasanafrotheriansynapomorphy,butprobablydevelopedindependentlyindifferentgroups.ImprovementinknowledgeregardingpostcranialcharactersoftheearliestSouthAmericannativeungulatesisnecessarynotonlyduetoitsimportanceinimprovingaccuracyofphylogeneticrelationships,butalsofortheinferencesmadeonpaleobiologicalfeatures.
【 授权许可】
Unknown
【 预 览 】
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