Correspondence Comments onEquus species as stratigraphic markers. Reality or wishful thinking?a andA review of Equus stenonis Cocchi (Perissodactyla, Equidae) and related formsa by A. Forsten

AbstractInthisletterwecommentontworecentpapersbyForsten(1998,1999).Intheformer,theauthordiscussesthepossibilityofusinghorsespeciesasstratigraphicmarkers.Thelatterisareviewof Equusstenonis forms,andalsoemphasisesthisapproach.Bothpapersareveryinterestingsinceoneofthemostquali"edspecialistsonfossilhorsescontributestherewithherownideastotheopendebateonthesystematicandstratigraphicvalueoftheEuropeanhorses.However,webelievethatsomeaspectsofForsten'spaperscanbeanalysedinadi!erentway. 2001ElsevierScienceLtd.Allrightsreserved. 1.HorsesasstratigraphicalmarkersForsten(1998,p.1097)wrote:`Variousschemeshavebeenproposed(BonadonnaandAlberdi,1987,Table2;AlberdiandRuizBustos,1989,Cuadro1;Azzaroli,1990,Fig.5),whichusefossilspeciesoftheequidgenus Equus asstratigraphicmarkersinthePlioceneandPleistocene.Accordingtotheseschemes,aspeciesofhorsede"nestheage of the fossil faunas in which it occurs and, corre-spondingly,theageofafossilfaunade"nesthespecies(even&subspecies')ofitshorsea.Whileitispossibletoestablishtheageofarockonthebasisofataxon,itisnotpossibletodetermineataxononthebasisofitsstratigraphicposition.Consequently,weagree with Forsten (1998, p. 1097) when she wrote`2Horsespeciesshouldbeidenti"edontheirmorpho-logy, not on their stratigraphic agea. But we have notfoundanytaxonomicdeterminationbasedontheageofthefossilhorsesinthosepaperscitedbyForsten.In our opinion, Forsten confuses the way this datahave been used. Taking as an example the paper ofAlberdiandRuizBustos(1989),theseauthorsdonotuseanytaxonomicdeterminationbasedonthestratigraphicpositionofthefossils.Forexample,thetibiafromBar-rancode Can uelas-1a, geographicallyand stratigraphi-cally close to HueHlago locality, is equal to those fromHueHlago, and it was identi"ed as