Abstract: The tithonic faciès of pelagic limestones which are Upper Jurassic-Lower Cretaceous in age located inthe studied area are rich in Caipionellids, The stratigraphie columnar section are measured to study biostratigraphy ofCalpionellids and to define the boundary of Jurassic-Cretaceous, The thickness of this unit is about 500 m. According tothe sedimentologic and pétrographie studies of thin section of collected samples of this limestones are micrite. Accor«ding to the result of paléontologie and biostratigraphic studies, this unite contents 4 Calpionellid biozones such as:Crassicollaria intermedia Zone (at the bottom of upper Tithonian), Calpionella alpına Zone (at the top ofUpper Tithonian), Calpionella elliptica Zone (Lower Berriasian) and Calpionellopsis simplexCalpionellopsis oblanga Zone (Upper Berriasian), On the other hand, the age of this unit is determined as Tithonian-Hautrivian (?) and a new species of Calpionellid (Crassicollaria remanei n, sp.) is found. These biozones arecompared with the biozones which are previosly described. This tithonic facies limestones are also compared with theother similar facies located in the Pontid zone, The boundary of Jurassic - Cretaceus is determined 185th meter of stratigraphie section that Calpionella elliptica Cadisch is appeared.