HOW NEOICHNOLOGY CAN INFORM ICHNOTAXONOMY

The strictly morphologic approach taken by many ichnotaxonomists during the past half-century has aided the acceptance of ichnology among geologists, who were gratified to find another tool to infer ancient environments. However, it has also led to an increasing disconnect with biology. Trace fossils not only offer insight into physical parameters, but other aspects of once-living ecosystems: the kinds of organisms that made the traces, how they lived and moved, what they ate, and much else besides. Currently, trace fossils are distinguished largely on the basis of morphologic characters that are easy for humans to read but were not necessarily the most significant to the animals that made them. For example, an ichnogenus of burrows might be split into species on the basis of smooth, longitudinally striate, or transversely striate sculpture, while ignoring other features. But this approach often places very different traces in the same ichnotaxon. A holistic approach would address all salient features of the traces, considering their function during the life of the tracemaker. It would also take into account the changes to traces made by animals as they grow older. This avoids the absurdity, for example, of giving different names to fiddler crab burrows, which in life are modified from a simple I to J, U, and W shapes. Such ichnotaxa will have to be based on the morphologic characters that are constant through time, and will require a more complexly developed ichnotaxonomy – one that recognizes the similar complexity of life, and moreover will yield a richness of information from the geologic record.