Stuck in the middle. A geographical appraisal of the oldest insectivores – and a marsupial – from the Vallès-Penedès Basin (early Miocene, Catalonia, Spain)

Marc Furió,Isaac Casanovas-Vilar,Lars W Van Den Hoek Ostende

doi:10.5852/cr-palevol2020v19a1

Abstract

The Vallès-Penedès Basin in Catalonia (NE Spain) forms a biogeographically important connection between central Europe and the Iberian Peninsula. Whereas this is well documented for the late middle and early late Miocene, the early Miocene sequence has received far less attention. New excavations yielded micromammal assemblages from the Ramblian and early Aragonian. Among the euliphotyhplans and metatherian studied, we recognize seven non-soricid species (Amphiperatherium frequens von Meyer, 1846, Galerix symeonidisi Doukas, 1986 and Galerix remmerti van den Hoek Ostende, 2003, Desmanodon daamsi van den Hoek Ostende, 1997, Heterosorex neumayrianus Schlosser, 1887, Chainodus sp., Plesiodimylus sp.) and six species of shrews (Paenelimnoecus sp., Miosorex sp., cf. Clapasorex, cf. Oligosorex, cf. Florinia sp. and Soricinae indet.). They confirm the intermediate position of the Vallès-Penedès also at the time of the older faunas, but show that differences with the Iberian inland were less pronounced. These differences can be explained by higher humidity in the coastal region, as indicated by the presence of dimylids. The differences between this coastal area and inland basin confirm the potential of coastal regions as migration corridors.

Highlights

At the end of the early Miocene, a remarkable transition takes place in the micromammal fauna of western Europe, when cricetid rodents, after a period of almost complete absence, enter the continent, ending the reign of the glirid/eomyid dominated faunas (Daams & Freudenthal 1990)
The main difference lies in the presence of the dimylids Chainodus (Ramblian only) and Plesiodimylus. These dimylids occur in the Iberian Peninsula only in the coastal basins
The occurrences of the other eulipotyphlans largely mirror those from the Daroca-Calamocha area, with the exception of Soricinae gen. et sp. indet from el Canyet, which forms a unique and tantalizing early record of its subfamily

Summary

Introduction

At the end of the early Miocene, a remarkable transition takes place in the micromammal fauna of western Europe, when cricetid rodents, after a period of almost complete absence, enter the continent, ending the reign of the glirid/eomyid dominated faunas (Daams & Freudenthal 1990). This change in the rodent faunas is well documented in Spain as well as other parts of Europe and marks the transition between MN Units 3 and 4 (see Material and methods section), coinciding with the boundary between the Ramblian and Aragonian European land mammal ages. Hordijk et al (2015) included descriptions of the insectivores in their paper on the locality of Montalvos 2 and Crespo-Roures et al (2018) published Plesiodimylus finds from Mas d’Antolino B-5, and the other dimylid finds from the Ribesalbes-Alcora Basin were, in combination with the Talpidae of these localities, published by Crespo-Roures et al

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Discussion

Conclusion