Palaeoecological models, non-uniformitarianism, and tracking the changing ecology of the past

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Abstract
Palaeoecological models are commonly used by palaeontologists and sedimentary geologists to reconstruct ancient palaeoenvironments. In order to illustrate the ways in which palaeoecological models develop as new information is discovered, four examples are discussed: (1) reefs and fossil cold seeps; (2) biofacies models for strata deposited in ancient oxygen-deficient environments; (3) palaeoenvironmental distributions of post-Ordovician stromatolites; and (4) onshore-offshore trends of trace fossils. The development of physical sedimentological and geochemical criteria that can independently be used for evaluating ancient depositional environments provides a base line with which to assess palaeoecological change through geological time. Thus, the possibility now exists to free palaeoecological models and the study of ancient ecology from traditional uniformitarianism and Lyell’s dictum that the ‘present is the key to the past’, so that palaeoecological models may be developed which are useful for segments of time not anchored in the present. This approach will also be essential for evaluating the changing ecology of the past, which at present is only poorly understood. Future development and independent testing of such palaeoecological models will allow a more complete appreciation of the changing roles of environment, ecology and evolution in the history of life.