Vörös A. szerk.: Fragmenta Mineralogica Et Palaentologica 18. 1996. (Budapest, 1996)

synecology (communities and death assemblages) of Triassic ammonoids on the example of Chinese faunas. The results and conclusions of this paper are so straightforward and impulsive that anyone who has a good data set on Triassic ammonoids might feel to be provoked to apply them. The Balaton Higland with its rich Middle Triassic ammonoid faunas seems to be appropriate for applying and testing the results of WANG & WESTERMANN (1993). Systematic collections in the last decade provided thousands of ammonoid specimens from dozens of localities of the Balaton Highland. Numerous sections, encompassing the Upper Anisian to Lower Ladinian interval, have been collected bed-by-bed and their detailed biostratigraphical subdivision has been published (VÖRÖS 1993, VÖRÖS et al. 1996). The study of the local paleogeography shows that these sequences have been deposited in different sedimentary environments (BUDAI & VÖRÖS 1992, 1993, VÖRÖS et al., in press). The aim of the present paper is to study the distribution of the Middle Triassic ammonoids of the Balaton Highland according to the different paleoenvironments and to analyse the temporal changes in the composition of faunas in order to trace the changes in bathymetry. The present study was supported by the grants No. 3185 and No. 7631 of the Hungarian National Research Fund (OTKA). MATERIAL In the last decade, in the course of the detailed geological mapping of the Balaton Highland by the Hungarian Geological Survey, several new localities exposing the Upper Anisian to Lower Ladinian stratigraphie interval have been found and a lot of loose ammonites from these levels have been gathered by T. BUDAI, G. CSILLAG and L. DOSZTÁLY (HGS, Budapest). In the most promising places artificial exposures, trenches have been dug and detailed bed-by-bed collections have been made. The most important localities and sections have been described and their ammonoid faunas have been listed elsewhere (VÖRÖS 1993). The biostratigraphical subdivision given in the cited paper was slightly revised recently, and in VÖRÖS et al. (1996) the following stratigraphical scheme (Table I) was published: Table I. The biostratigraphical scheme and nomenclature, used in the present paper. STAGES ZONES SUBZONES CURIONI SECEDENSIS Avisianum LADINIAN REITZI Reitzi Licpoldti Felsoeoersensis Pseudohungaricum ANISIAN TRINODOSUS Camunum Trinodosus