| Description |
Trace fossils are the result of animal behaviors, such as burrowing and feeding, recorded in the rock record. Previous research has been mainly on the systematic description of trace fossils and their paleoenvironmental implications, not how animal behaviors have evolved. This study analyzes behavioral evolution using the quantification of a group of trace fossils, termed graphoglyptids. Graphoglyptids are deep marine trace fossils, typically found preserved as casts on the bottom of turbidite beds. The analytical techniques performed on the graphoglyptids include calculating fractal dimension, branching angles, and tortuosity, among other analyses, for each individual trace fossil and were performed on over 400 trace fossils, ranging from the Cambrian to the modem. These techniques were used to determine various behavioral activities of the trace makers, including feeding and behavioral evolution. Graphoglyptids have been previously identified as representing mining, grazing, farming, and/or trapping. By comparing graphoglyptids to known mining burrows and grazing trails, using fractal analysis, it was possible to rule out mining and grazing behaviors for graphoglyptids. To determine between farming and trapping, a review of all known trapping burrows was required. The hypothesis that graphoglyptids were trappers was based entirely on the hypothesized feeding behaviors of the worm Pciraonis. Close examination of Paraonis burrows indicated that the burrows are not traps. This means that, since Paraonis does not trap prey, graphoglyptids should not be considered traps either. Therefore, graphoglyptids likely represent farming behavior. This study also shows that previous interpretations of graphoglyptid behavioral evolution was far too simple. The results of the morphological analyses indicate that major changes to the behavioral evolution occurred during the Late Cretaceous and the Early Eocene. Previous hypotheses about Late Cretaceous evolutionary influences were validated. However there were additional influences like the Paleocene-Eocene Thermal Maximum that were not overly emphasized before. Finally, of the many theories about the driving force of evolution, chaos theory has often been overlooked. Chaos theory is a powerful tool, such that, by knowing the similarities between chaos theory and evolutionary theory, it may be possible to map out how environmental changes could shift the evolution of a species. |
