Cranial morphology and variation in the iconic Villafranchian proboscidean Mammuthus meridionalis (Nesti, 1825) from the type locality of Upper Valdarno (Tuscany, Italy)

The aim of this article is to provide a detailed description of the cranial anatomy of Mammuthus meridionalis (Nesti, 1825) based on the type material from Upper Valdarno (UV), Italy. The UV sample includes both male and female individuals and a fragmented skull of a new-born, allowing us to highlight variation in cranial features linked to both sexual dimorphism and ontogeny. The southern mammoth occupies a central role in elucidating the evolutionary pattern of mammoths during the Early Pleistocene (Villafranchian Land Mammal Age), when the first cold adapted mammoth species, Mammuthus trogontherii (Pohlig, 1885), the steppe mammoth, originated. A detailed knowledge of the morphology and variation of the skull of this iconic Villafranchian species is crucial to clarify the complex systematic and evolutionary pattern of mammoth evolution during this time interval. The study supports the conclusion proposed by Augusto Azzaroli more than forty years ago, that the Upper Valdarno mammoth population was not directly ancestral to the steppe mammoth, which dispersed to Western Europe at the beginning of the Middle Pleistocene.