Final answer:
The correct answer is D. Ichnology, which is the study of trace fossils that provide insight into the past behavior and environments of organisms, different from Taphonomy, which deals with fossilization processes.
Step-by-step explanation:
Understanding Substrate Variations in Fossil Traces
When discussing the substrate variations altering the traces of one taxon, the correct answer is D. Ichnology. Ichnology is the field of study that examines trace fossils, which include things like burrows, footprints, and even coprolites (fossilized excrement). Trace fossils provide significant information about the behavior and environment of past organisms. Taphonomy, on the other hand, deals with the processes of preservation and fossilization, which is not the focus of this question regarding traces in substrate variation. Understanding trace fossils through ichnology can reveal important information about ancient environments, from water depth and salinity to the presence of life and its interactions with the sediment. The study of substrate and its impact on trace fossils helps to reconstruct past ecosystems and the living conditions within them. It is an essential branch of paleontology, offering clues about the daily activities and habitats of extinct species.