The paper presents new evidence on the small and large mammal fauna from the Trlica locality, Montenegro, based on our records from the 2010 – 2014 excavations. It is shown that the lower layers of the locality correspond to the Early Pleistocene, and the upper layers are dated as the beginning of the Middle Pleistocene. The results obtained allow us to characterize the environment in which the oldest hominid migrants dwelt in this region of South-Eastern Europe. Within the interval 1.8–1.5 Ma, there was a relatively cool climate in the region. At the beginning of the Middle Pleistocene, the climate became milder; the areas occupied by forests, including broad-leaved forests, increased. The presence of Lagurini throughout the section is evidence of the existence of local areas of steppe in northern Montenegro during the Early Pleistocene and first half of the Middle Pleistocene.