Paleoecología del género Anchitherium von Meyer, 1834 (Equidae, Perissodactyla, Mammalia) en España: evidencias a partir de las faunas de macromamíferos

Abstract

The paleoecology and evolution of the equid Anchitherium VON MEYER, 1834 is studied in this paper by means of multifactorial analysis (principal components analysis, discriminant analysis) of the Ramblian-lower Vallesian large mammal faunas from the Iberian Peninsula. Joint analysis of subtropical and tropical recent faunas and Miocene faunas allow the establishment of several environmental characteristics (temperature, thermal seasonality) of the ecosystems of those Miocene communities. Our results indicate that it is possible to infer the biome of a locality based on its macromammal fauna. It has been able to infer the presence in the Iberian Miocene of temperate evergreen forests, tropical deciduous forests and savannas. A relationship is observed between the relative size of the den- tition regarding the corporal size in Anchitherium and the temperature variations. Populations that occupied more thermally seasonal environments presented a relatively bigger dentition regarding their corporal size than the non-seasonally environment inhabitants. This could be related with a diminished consumption of fruits caused by a lesser fruit availability in the more thermal seasonality areas, and a higher consumption of leaves, less nutritive than fruits. The relative abundance of Anchitherium in the fossil local faunas seems mainly settled by temperature, being more abundant in faunas from colder fossil sites. This fact could be related with the environmental conditions that Anchitheriinae had to overcome to cross Beringia before reaching Eurasia. Biomes occupied by each Anchitherium species are studied. The two clades proposed by SÁNCHEZ et al. (1998) shown a similar behaviour. More or less ubiquitous species, adapted to dense forest environments, are substituted by more derived species adapted to ecosystems with a dry station (tropical deciduous forests and savannas), the predominant biomes in the Iberian Peninsula during the studied period. This process is more pronounced in the second lineage than in the first one. Another ubiquitous species, the northern immigrant A. hippoides come into the Iberian Peninsula in MN 6 zone and replace the rest of species. This process is related with the progressive increment in environmental humidity causing a faunal reorganization. Finally an environmental scenario for the evolution of Anchitherium in Spain is exposed. An alternation relationship as faunal dominant group during the Miocene between Equidae and Rhinocerotidae is shown