Fossil sea lilies of the genus Isselicrinus Rovereto, 1914 from the lower Oligocene, Eastern Rhodopes (Bulgaria)

Fossil sea lilies of the genus Isselicrinus Rovereto, 1914 were found near the village of Raven, Momchilgrad Municipality, in the Eastern Rhodopes in 1978. They were recovered from the rocks of the Raven complex. The latter is composed of rhyolite pyroclastics with layers of reef limestones. With the Ar/Ar method, the pyroclastics of thе Raven complex have been dated as 31.19–30.97 Ma (early Oligocene). The presence of reef limestones suggests shallow coastal waters with normal salinity and a warm climate, in which Isselicrinus lived. These were the outskirts of a tropical basin, inhabited by faunas, which today have their descendants in the tropical areas.