Matskási István (szerk.): A Magyar Természettudományi Múzeum évkönyve 79. (Budapest 1987)

Kecskeméti, T.: Contributions to the phylogenetic connections of Nummulites species

The groups are derived from the 3 ancient forms generally adopted: N. froasi, N. solitarius and N. deserti. N. fraasi was the source of the N, laevigatus and the N. distans-irregularis groups. N. laevigatus group The members of the N. laevigatus group developed from N. fraasi that spanned the Late Paleocene to Early Ilerdian interval. At Middle Ilerdian N. laxus, the group is split into two branches — one with a tightly coiled spire and one with a loosely coiled one. The tightly coiled branch proceeds through N. couisensis and N. beamensis, forms of Ilerdian age, reaching the Lower Cuisian N. jacquoti and, subsequently, the Middle-Upper Cuisian N. praelaevigatus. N. praelaevigatus appears to be an important taxon in the phylogeny of the laevigatus-group. It is its characters that exhibit the most obvious genetic relationship with N. laevigatus. This connection was traced by SCHAUB first directly from the source (HOTTINGER, LEHMANN & SCHAUB 1964) and then through the Upper Cuisian N. aff. praelaevigatus (SCHAUB 1966a). Lately, PAVLOVEC (CIMERMAN, PAVLOVEC, PAVSJC & TODESCO 1974) has changed SCHAUB'S N. aff. praelaevigatus to a new species which he has named N. quasilaevigatus. Lower Lutetian N. laevigatus should be regarded as a stable and strikingly important member of the lineage, owing to its simultaneous occurrence over a large area and its shortlived existence and to its homogeneity due to its comparatively narrow variability range. The further course of development of the lineage can be studied on Hungarian material as well, the relations between the particular taxa being more simple and more easily traceable. In the higher intervals of the Lutetian, N. laevigatus is followed by bigger and flatter taxa that are interconnected by a definite trend in septal curvature and reticulation. The trend is manifested in chambers becoming longer and, at the same time, less tall (this results in a progressively more tightly coiled spire), in a reduction of the curvature of the septa and increasing complexity of reticulation. N. laevigatus is followed by N. sordensis, form having longer chambers, heavily curved septa and a rather intricate reticulation, which is new to the Hungarian Nummulites fauna only as far as its name is concerned. In reality, it is identical with a nomen nudum, N. ungarica, of HANTKEN (in: HARPE 1881, p. 129). The stage of continued chamber elongation (chamber index 2-3) is represented by N. carpenteri; the septal curvature decreases and the reticulation providing the surface sculpture is more complicated than that of N. sordensis. The biggest and most differentiated species of this lineage is the Upper Lutetian N. brongniarti, being characterized by extremely long chambers (chamber index 5-6), fairly curved septa and extremely complicated and fine reticulation. N. brongniarti is the final member of the branch of tightly coiled spire, the laevigatus-brongniarti lineage getting extinct with it. The branche of tightly coiled spire evolves through the Ilerdian N. exilis and N. involutus and it reaches, through the intermediary of the Cuisian N. planulatus and N. aquitanicus, the loosely coiled equivalent of N. laevigatus represented by the Lower Lutetian N. britannicus. In passing, N. planulatus looks like a nodal point in phylogeny, from which N. manfredi issues in Late Cuisian time and TV. hagni does so in the Early Lutetian. It is noteworthy that N. aquitanicus shows a great deal of characters that are akin to N. laevigatus, but the differences in spiral pattern between the two species are already so marked that they suggest that the relationship must have slackened a long time before (probably in EarlyMiddle Cuisian time).