Vörös A. szerk.: Fragmenta Mineralogica Et Palaentologica 10. 1981. (Budapest, 1981)

pieces are preserved from something. However, it is also accidental what remains at all. It is natural in palaeontology to operate with error limits; at any rate, this does -not justify committing further errors. On the basis of the principle "much from many and little from few" there remained more of thoBe species that were more numerous than from those existed in smaller numbers. During the history of the Earth may of course have occurred such processes, as the dissolution of calcite skeleton, which fundamentally change the original conditions. In such cases the method should be applied reasonably; its mechanical application apparently leads to serious mistakes. The characteristics and the surroundings of biocoenoses are represented most distinctly by the prevailing spécii. In a given environment obviously those spécii spread over a large territory for which the given conditions are optimal. Those represented by just a few specimens are probably confined to micro-climates; they are relics found shelter in favourable ecological niches or represent elements springing up later, when circumstances change. In case of floras the application of the quantitative method has been attacked with the' argument that when a great number of leaveB of the same tree are found, these are regarded as individual units when analysing the fossil-flora. This, however, is excluded in the case of continental plants in clayey-sandy littoral sediments: the leaves having necessarily been subject to transportation; chance of finding a great number of the leaves of the same tree deposited in the sediment is reduced to minimum. It must however, be reckoned with in case of strictly autochthon floras. Diversity Is a characteristic feature of biocoenoses. This notion has long been recognised also in palaeontology, but when comparing several biocoenoses it needs computations to determine exactly which of them Is more diverse. The determination of diversity makes it possible to gather a great deal of valuable information about biocoenoses. The more diverse an assemblage the more stable It is. This Is natural: if, for example, there are only two species one of which perishes in the course of some negative effect the change will be 50% whereas in case of an assemblage with one hundred species the change will be only 1%. The application of this method yields great help in paleoblogeographical studies. Conclusions drawn from the comparison of floras/faunas of larger territories may be subjective and therefore different. Therefore it is useful if the author, in addition to his or her own opinion, gives a number of objective figures. The comparison of these is much quicker, more exact and simpler. As very few authors give specimen-numbers when analysing fossil floras and faunas the Indices cannot be calculated afterwards except by means of the semi-quantitative method on the basis of species lists. It would be beneficial to perform the qualitative evaluation when working on new floras/faunas, as well as when revising old ones. SUMMARY The Upper Oligocène (Egerian) Many Formation of the Tatabánya basin yielded macroflora in three places. The floras show similarities of composition. The largest of them (Vértesszolos) contains also Taxodiaceae and Pinaceae, the other two only Clnnamomum and deciduous remains. All the three floras Bhow the mixing of Paleotropical and Arctotertiary elements. They show only minor differences as to flora families since they belong to floras of the same age and of adjacent territories. They are related mainly to South-East Asian, in leBser measure to North-American floras. The composition of the flora suggests subtropical climate similar to that of South-East Asia today. To characterize each flora, as well as to compare the three, indices have been proposed using se ml-quantitative and quantitative methods. The equation of Jaccard, Koch, Sjirensen, Shannon and Horn have been used. The results are visually demonstrated by the charts Indicating that the floras of Vértesszolos (Baromállás) and those of Tatabánya are the nearest relatives. Less similarity has been found between the floras of Tatabánya and Tarján, whereas the floras of Vértesszolos and Tarján show the least similarity. The method of quantitative analysis has been widely used in recent literature, but it is not favoured in palaeontology. One of the reasons for this is that such evaluation demands full investigation (each specimen has to be taken Into consideration). The other Is that the accidental nature of fossllization raises doubts about the usefulness of the method. Selective fossllization is such a factor indeed, that cannot be reconstructed, but this alone does not provide good reason to disregard realities in favour of (further) subjective opinions. The method of course is only one of the possibilities, yet its wider application in palaeontology might be profitable. It would probably promote the advancement of palaeontology, it could facilitate the quicker and more exact comparison of floras/faunas both in time and space.