The dolmen known as Shepsi was accidentally discovered on the Black Sea coast (Tuapse region, Russia). Radiocarbon dates show that the classic trapezoidal construction of the Caucasian dolmens with a port-hole appeared in the region as early as 3250 BC. The distinctive structural characteristic for dolmens of that time was a floor slab laid between the side slabs, which were embedded in the ground. The material complex and 14C dates show that this type of dolmen coexisted with the Novosvobodnaya-type of the Maikop culture, located on the northern slope of the main Caucasus ridge. This leads to a new hypothesis concerning the regional origin and further development of the megalithic structures in the western Caucasus.