Ecological and L-system based simulations of trace fossils

摘要

Trace fossils represent the preserved interactions of trace making organisms with their environment. The form of traces should result from complex interactions among the organism's morphology, the behavior being carried out, the organism's perception of the environment, and the heterogeneity of the environment. Existing mathematical models for the biological formation of traces have tended to focus on a limited repertoire of behaviors, such as grazing. They do not include realistic patterns of environmental heterogeneity, differences in perception, or multiple behavioral responses. In addition, there have been almost no attempts to model 3-D traces, or traces that branch or anastomose. New models for grazing and crawling traces can be built on current research by ecologists into animal movement patterns and their interaction with environmental heterogeneity. These models explore the interactions of alternative spatial patterns of environmental heterogeneity with different perceptions and behavioral responses to it. They have the potential for suggesting how behavioral patterns for a given trace making organism might change as a function of environmental differences, such as resource distribution. This could be a useful tool for determining such patterns of spatial heterogeneity in ancient environments. A second approach can be based on recent developments in the computer-based study of morphogenesis. This technique utilizes L-systems and related methods for the generation of branching and 3-D theoretical morphologies. L-system descriptions can be quite complex and can incorporate realistic concepts of growth, including external environmental factors and signal transmission. They have been used previously for the production of simulated plants of startling realism. By altering the parameters used to generate the simulated fossils, a theoretical morphospace for trace morphology could be constructed.