Abstract

MURELAGA, Xabier; PEREZ-RIVARES, Francisco Javier; VAZQUEZ-URBEZ, Marta  and  ZULUAGA, Ma. Cruz. New biostratigraphic and paleoecologic data from the middle Miocene (Aragonian) from the Tarazona de Aragón area (Ebro Basin) Zaragoza province, Spain. Ameghiniana [online]. 2008, vol.45, n.2, pp.393-406. ISSN 1851-8044.

In this contribution the vertebrate microfossils of two new localities (Melero-20 and Melero-30) near Tarazona de Aragón village (Ebro Basin, Spain) are described. The fossil association is dominated by micromammal fossils, represented by Rodents (Sciurids, Cricetids and Glirids), Lagomorphs and Chiropters, and allows to situate Melero-20 in the local biozone E (European Mammal Neogene Zone, MN5) and Melero-30 between the local biozones F and G1 (MN6), both in the Miocene. The revision of the Tarazona de Aragón and El Buste mammal localities, at the bottom and from the bottom of the local succession, gives the following new biostratigraphic assignation: Dc-Dd (MN5) and G2 (MN6), respectively. The described remains were accumulated in ponds or shallow lakes colonized by plants, with common desiccation and pedogenetic processes. The evolution of rodent association through the local succession indicates a relative climate cooling. The vertebrate diversity decreases from base to top, which may be related to a temperature decrease through time. A similar temperature and diversity decrease has been recognised in the Calatayud-Teruel Basin (NE of Spain) during the same time interval. This decrease could be associated with the cooling that follows the Mid-Miocene Climatic Optimum. Even though the rodent association does not reveal changes in relative humidity, clay mineralogical analyses suggest an arid environment for the Tarazona de Aragón level, the older in the succession, a humidity increase for Melero-20 and a decrease for Melero-30.

Keywords : Miocene; Aragonian; Ebro Basin; Bioestratigraphy; Paleoecology; Paleoclimatology.