Nuevos datos bioestratigráficos y paleoecológicos del Mioceno medio (Aragoniense) del área de Tarazona de Aragón (Cuenca del Ebro, provincia de Zaragoza, España)

Xabier Murelaga, Francisco J. Pérez Rivarés, Marta Vázquez Urbez, Ma. Cruz Zuluaga


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.

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