The Aragonian type area revisited; comments on paleontology and stratigraphy.

Abstract

In a recent study of van der Meulen and coauthors, the fossil rodents Fahlbuschia, Pseudofahlbuschia and Renzimys from the Aragonian type area (Calatayud Basin, Spain) were synonimized with Democricetodon. On the basis of the relative chronology provided by Daams and coauthors in an earlier study, these authors construed two evolutionary lineages, distinguished by size. One of these lineages contains Fahlbuschia koenigswaldi (Freudenthal, 1963) and the other one Democricetodon moralesi van der Meulen et al. (2004) but, in view of their great similarity, we consider D. moralesi to be a synonym of F. koenigswaldi.The relative stratigraphic position of some fossil mammal localities is difficult to establish in the Aragonian type area because it is affected by folds and faults. Early studies of Daams and Freudenthal subdivided the local zone D into D1, D2, D3 and gave a scheme of the stratigraphy in which the fossiliferous locality Valdemoros 1A is considered to be older than Valdemoros 3B. But Daams and coauthors came to the opposite interpretation in a later study, and divided zone D in Da, Db, Dc, Dd. But, new field data presented here enforce the original interpretation in which Valdemoros 1A is older than Valdemoros 3B. This leads to the conclusion that the division of local zone D into Da to Dd has to be discarded, and substituted by the formerly proposed zonation D1-D3.