Variation inHibolithes arkelli arkelli—2

Abstract

Abstract Multivariate statistical tests on random samples of the belemnite Hibolitbes arkelli arkelli Stevens drawn from localities at Puti Point (Kawhia Harbour) and Ngapohoi Stream (east of Kawhia Harbour) show that the measurement vectors of certain parameters are highly likely to be from populations with different variance-covariance matrices. The vectors of means are different too, although no individual measurement produces a significant mean difference. The evidence is strong that the Puti Point specimens are from a population which is clearly different from the population found at Ngapohoi Stream. The means, standard deviations, and correlations of the measured variables were studied in detail. The main conclusion is that there is a significant age difference in the two populations and that the Ngapohoi Stream sample was collected from beds which are geologically older that those at Puti Point. Statistical differences between samples are of an evolutionary nature; differences within samples are at least partly ontogenic.