Biometrical studies of Early Neogene larger Foraminiferida from Australia and New Zealand

Abstract

New and previously defined parameters for Cycloclypeus, Heterostegina, Miogypsina and Lepidocyclina have been treated statistically using standard univariate techniques, and multivariate methods have been used with Lepidocyclina (Nephrolepidina). The univariate studies show that three parameters for Cycloclypeus (pc, Spc4+5, log D1 of O'Herne & van der Vlerk, 1971) are of equal biostratigraphic value; for Heterostegina two new ones (N0 and S4+5) appear useful for correlation, but need to be tested over a wider geographic area; for Miogypsina, which is rare and has a limited stratigraphic range in the areas studied, only parameters X and V are useful for taxonomic and biostratigraphic purposes; for Lepidocyclina (Eulepidina) both A (of van der Vlerk, 1959a,b) and the new parameter LA appear to be useful for correlation, but a realistic appraisal of these must await detailed studies elsewhere. For L. (Nephrolepidina) two new parameters (E,F) and those of van der Vlerk (1959a,b — parameters A and B), and O'Herne & van der Vlerk (1971 — parameter dc) have been used; of these F is the most useful, with B being of only local usefulness within Australia, and A, dc and E being similarly useful only in New Zealand. Multivariate studies with L. (Nephrolepidina) show that parameter F is largely responsible for the groupings obtained. Cycloclypeus and Lepidocyclina (Nephrolepidina) seem to be the only larger foraminiferids suitable for biostratigraphic correlation within Australia. The biometric results suggest that the rates of evolution of the New Zealand larger foraminiferids were different from those of the Australian region.