ABSTRACT. The Middle Miocene (Badenian, Sarmatian and Pannonian) deposits from the region of Bistriţa, between the localities: Susenii Bârgăului, Livezile, Bistriţa, Sărata, Sărăţel, Budacu de Sus (Transylvanian Basin) have been analysed from the nannofloral point of view. The nannofossils are relatively scarce, excepting the ones related to Lower Badenian deposits. Only the fossil index for NN5 Zone -Sphenolithus heteromorphus, and for NN6 Zone -Discoaster exilis have been identified.

The paper presents in synthesis the conids from Lăpugiu de Sus, especially those which are preserved in the collections of Palaeontology-Stratigraphy Museum of the Babeş-Bolyai University. Conids, carnivorous gastropods who lived in shallow waters from neritic zones, in warm seas, respectivelly subtropical to tropical, with a normal salinity, have been the most diversified gastropods at Lăpugiu de Sus during the Middle Miocene (Badenian). There are also species which could tolerate slight decreasing of salinity such as Conus (Conolithus) dujardini brezinae. It was remarked that the conids from Lăpugiu de Sus lived in the conditions of shore-offshore zones where the temperature of water was about 21ºC.

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The palaeoclimate during the Miocene of the Transylvanian Depression (Romania) is interpreted mainly by the response of calcareous nannoplankton, microfauna (foraminifera), molluscs and mammals (rhinoceros) assemblages.The first significant palaeoclimatic event is recorded during the early Miocene. The climatic warming at the level of the Vima Formation was followed by a more important warming during the Eggenburgian, which is preserved in the fossil record of the Corus Formation. During the Ottnangian, a cooling episode is recorded in the Hida Formation, probably related to Atlantic and Boreal influences. The climate on land was probably subtropical, humid, but much cooler than the Eggenburgian, as the remains of rhinoceros from this formation indicate.The Middle Miocene marine sub-tropical assemblages are present in the Dej Formation (early Badenian), but towards its upper part sub-tropical species become scarce. The endemic elements, with boreal influences, are recognized in Kossovian strata. On land, the Moravian rhinoceros also suggest a sub-tropical climate, with marshy, densely afforested areas. Another rhinoceros found in the upper part of the Moravian, indicates a tendency to the continentalization of the climate. The early Sarmatian began with short period of warming, followed again by a cooling episode (Feleac Formation).The last significant warming is recorded in the Late Miocene, during the Pannonian (Lopadea Formation). The small aceratheres from the Pannonian suggest marshy areas with a relatively warm climate.

Three sections from the upper Miocene (Pannonian) of the Guşteriţa quarry – Sibiu (the southern border of the Transylvanian Basin) were investigated in detail. The main part of the research was based on calcareous nannofossil analysis to which some aspects on molluscs and ostracods fauna, together with sedimentological remarks were added. The calcareous nannofossil assemblages from Guşteriţa quarry were compared with seven other previously analyzed sections from the western border of the Transylvanian Basin: Aiud area (Geoagiu, Gârbova, Gârboviţa, Lopadea exposures and Decea quarry) and Sibiu area (Vurpăr and Apoldu exposures). The Pannonian calcareous nannofossil assemblages are abundant at some levels and contain mostly species of the genera Isolithus and Noelaerhabdus.