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 palaeontologist Miquel Crusafont in 1950 to mark the arrival of the equid Hipparion in Europe.
The remaining European palaeofaunas, however, had been around since the Middle Miocene, including the moschid Micromeryx (a musk deer), the cervid Euprox, the suid Listriodon, and the felids Sansanosmilus and Pseudaelurus, 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 Aragonian artiodactyls, including the antelope Protragocerus, the bovid Miotragocerus, Listriodon, and the suids Hyotherium and Parachleusastochoerus.
The end of the Vallesian, and the beginning of the Turolian, brought the extinction in the west of faunas dominated by the bovids and giraffids characteristic of the so-called sub-Paratethyan or Greek-Iranian province.