Dietary behaviour and competition for vegetal resources in two Early Miocene pecoran ruminants from Central Spain

摘要

Dietarybehaviourandcompetitionforresourcesareinvestigatedforthesmall-sizedruminantsAndegameryxGinsburg,1971andProcervulusGaudry,1877representativesoftwolargelydistinctstatesofdiversificationofpecorans.ResultsobtainedfromdentalmicrowearandmesowearmethodologiesareconcordantwithamixedfeederstrategyforthetaxafromtheEarlyMioceneenvironmentsoftheIberianChain(CentralSpain).Further,theSpanishtaxainvestigatedhadlessabrasivedietsthantheirrelativesfromotherssimilarlyagedlocalitiesinEurope.Thisfactraisesanimportantevolutionaryuncertaintyconcerningthetraditionalcharacterizationoffirstpecoransasspecializedbrowsers.Instead,datastronglycorroboratetherecentlyproposednotionthatsomePecoraruminantlineageswereabletoconsumeamixtureofbrowseandgrass,andthatwereoriginallyfacultativemixedfeeders.However,thereisalargedegreeofvariationoftheirdentalwearfeatures.Specieswerenotdependentonalimitedtypeofvegetationand,consequently,wereabletoexploitdifferentfoodresources.Dentalweardataseemtoindicatethattheseruminantsdidnotcompeteforvegetation.Inaddition,lastAndegameryxandearliestProcervulusapparentlyhadasufficientlydifferentbodysizetopartitiontheavailablevegetationintermsofheightabovegroundleveltoeludecompetition.Bodysizedifferencecoupledwithanimportantdegreeofdietaryopportunismmayhavebeenfactorsnecessaryfortheircoexistence.