The theory and use of methods for the study of mammalian palaeoecology
Palaeoecology is one way of reconstructing the palaeoenvironment. The ecological and theoretical foundations underlying a number of palaeoecological methods are discussed and these methods are then applied to mammalian faunas from the fossil record. Three basic palaeoecological approaches are described: Indicator methods, population methods and community diversity methods. Ecological niche theory is used to relate these to neo-ecological concepts concerned with the distribution of species with respect to habitats and other species. Detailed consideration of the theory behind these approaches shows that indicator methods are only suited to recent faunas, while ancient faunas, and those containing large numbers of species, are best analysed using diversity methods. Climatic climax vegetation types of tropical and temperate regions are described, together with examples of their associated mammal communities. Each habitat supports a community with a distinctive adaptational structure which is related to the productivity, stability and physical complexity of the habitat. Palaeocommunities are often incompletely preserved, and the sensitivity of selected palaeoecological methods to species loss is tested in a series of simulations based on communities from known modern habitats. The results obtained form the basis for the interpretation of fossil faunas. Mammalian faunas from the European Pleistocene sites of Lazaret and Westbury-sub-Mendip are analysed using several methods, and it is seen that even when a fauna is rich and well-identified, different methods give slightly different results. Further analysis of a large number of Pleistocene faunas shows that extinct habitats can also be identified. The community structure of early Miocene faunas from East Africa is analysed and compared with modern tropical communities. It is concluded that the disappearance of the early Miocene hominoids and the subsequent radiation of the cercopithecines were part of a general change in the structure of African forest communities.