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

(2) Somewhat evolute platycones + oxycones. Morphology: Whorls are moderately evolute, sometimes with keeled or sulcate venter, the sculpture is rather strong. Middle Triassic examples: Beyrichitidae, Protrachyceratidae, Aplococeratidae. Habitat: "inner slope", with 100-150 m depth range. (3) Involute platycones + oxycones. Morphology: Whorls are involute and smooth ("streamlined"), with acute or keeled venters. Middle Triassic examples: Longobar ditidae, Hungaritidae. Habitat: "basin" with 150-250 m depth range. (4) Sphaerocones. Morphology: Whorls are mostly involute, depressed to compressed, subglobular (poorly "streamlined"), smooth, or weakly ribbed. Middle Triassic examples: Ptychitidae, Arcestidae. Habitat: "bathyal" (continental slope) with depth range down to 600 m. The above categories and criteria can not directly be applied to the case of the ammonoid faunas of the Balaton Highland because here the habitats (the paleoenvironments) does not seem to represent so wide variety and the morphogroups are represented by a narrower spectrum of genera as well. In fact, in the Middle Triassic of the Balaton Highland we may count with only two habitats: a shallower one, at the pelagic plateaus and a deeper one in the basins. Correspondingly, there is no reason to make so distinct differences between (or within) the ammonoid morphogroups. For the present case, in order to try to express the differences in paleo-depths, it seems to be enough to use the end-members of the spectrum given by WANG & WESTERMANN (1993). In this tentative, simplified model the morphogroup of "planulates + depressed coronates" is used to express the "shallow" (s. 1.) character of the environment, whereas the morphogroup of "sphaerocones" (in fact the Ptychitidae) is used to mark the "deep" (s. 1.) environment. More precisely, the high proportion of "coronates" (the strongly ornamented Ceratitidae: the genera Paraceratites, Asseretoceras, Megaceratites, Lardaroceras, Kellnerites, Parakellnerites, Reitziites, Ticinites and Stoppaniceras) is regarded as a marker of the "shallow environment", whereas the proportion of the "sphaerocones" (in the present case the Ptychitidae and Arcestidae) is taken as a measure pointing to the "deep environment". The other genera (e.g. Semiornites, Longobardites, Hungarites, Aplococeras) are considered as "intermediate" or "indifferent" from paleobathymetric point of view, at least on this scale. RESULTS Before the application of the above, intricate, though simplified, method based on WANG & WESTERMANN (1993) a qualitative empirical approach has been made to find some regularity in the distribution of the ammonoid genera in the Middle Triassic of the Balaton Highland, i.e. to find any relationship between the ammonoid distribution and the paleoenvironments. BRACK & RIEBER (1993, p. 487) gave a promising, short