TheVallesian age is a period ofgeologic time (11.6–9.0Ma) within theMiocene used more specifically withEuropean Land Mammal Ages. It precedes theTurolian age and follows theAstaracian age. The so-called Vallesian Crisis resulted in the extinction of several mammalian taxa characteristic of the Middle Miocene.
The term "Vallesian" was introduced by Catalan palaeontologistMiquel Crusafont in 1950 to mark the arrival of theequidHipparion in Europe. The remaining European palaeofaunas, however, had been around since theMiddle Miocene, including the moschidMicromeryx (a musk deer), the cervidEuprox, the suidListriodon, and the felidsSansanosmilus andPseudaelurus, and the Aragonian-Vallesian[Note 1] boundary does not represent a major shift in the European mammalian record. In contrast, the transition between Lower and Upper Vallesian corresponds to a major biotic crisis — the demise of most Aragonianartiodactyls, including the antelopeProtragocerus, the bovidMiotragocerus,Listriodon, and the suidsHyotherium andParachleusastochoerus. The crisis also affected rodents such as the familyEomyidae and most of thecricetids andglirids. They were replaced by species arriving from the east, Turolian in character: for example the suidSchizochoerus, the muridProgonomys, the bovidsTragoportax andGraecoryx, the hyaenidAdcrocuta, the felidParamachairodus, and the suidMicrostonyx.[1]
The Vallesian was a crucial period for the evolution of the European terrestrial fauna. During the Middle Miocene, the highly diversified mammalian fauna of the European forests were replaced by the faunas of the Late Miocene, adapted to a dry climate and to an open terrain. The beginning of the period is marked by the appearance and dispersal of the early horseHipparion throughout Eurasia. The so-called Vallesian Crisis resulted in the extinction of several mammalian taxa characteristic of the Middle Miocene. The end of the Vallesian, and the beginning of the Turolian, brought the extinction in the west of faunas dominated by thebovids andgiraffids characteristic of the so-called sub-Paratethyan or Greek-Iranian province.[2]