Cretaceous Carabidae (Coleoptera) from Orapa, Botswana
McKay, Ian James
A fauna of mid-Cretaceous Carabidae (Coleoptera), recovered from Orapa Diamond mine, Botswana is described. The carabids are similar to extant forms and include: the first record of a fossil of the subfamily Promecognathinae, Palaeoaxinidium orapensis (gen. et sp. n o v . ); the earliest record of a member of the Scaritinae; and ten specimens which are placed tentatively in the subfamilies Siagoninae (two specimens), Pterostichinae (three specimens), Anchomeninae (one specimen), and Harpalinae (four specimens); in addition two specimens cannot be placed in any particular subfamily. The manner of preservation of the fossils is described, and a taphonomic analysis of the site is attempted. The exact age of the sediments is discussed, and a palaeoenvironment is inferred from a study of the carabids, the rest of the fossil fauna, and the sediments. This fauna of carabids lived in a well-wooded crater formed by the eruption of a kimberlite. The climate of the time was seasonal, warm, and intermediate between tropical and temperate extremes. The morphological conservatism of the promecogna thine, and the apparent conservatism of the way of life of members of this group, provides support for the punctuated equilibrium pattern of evolution.
Thesis (Ph.D.)--University of the Witwatersrand, Faculty of Science, 1990.