Tricky, “Ich”-y Clues

Ichnofossil is a rather funny looking word, and frankly, it’s fun to say too – it is pronounced Ick-no-fossil.  Like I mentioned last week, these fossils are unique because they are not body fossils (i.e., bones, preserved skin, etc.), but merely traces.  They are evidence that something was moving around in and on top of the rock layers while the rock layers were still soft and just forming.  This indicates that the layers were deposited rapidly by Noah’s flood, not millions of years ago.

There are three basic things scientists can get clues about from fossils: 1) how the animals lived, 2) how they died, and 3) how they were buried.  Ichnology (pronounced “Ick-nol-ogy” the study of ichnofossils) is primarily concerned with how animals lived.  In the very strict and technical definition of ichnofossil, an ichnofossil must be associated with an animal’s behavior.  For instance, the traces of a trilobite being dragged through a flood current are technically not ichnofossils, because they do not indicate anything about the animal’s behavior, while the traces of the same trilobite pausing along its trail are ichnofossils, because they are an indication of the trilobite’s behavior.  Personally, I think that studying how the trilobite was being dragged along by flood currents would be much more fascinating than the former example, but it’s not officially an ichnofossil.

Ichnology is a rather tricky, detective-like science, because we don’t know what animal made many of the specific ichnofossil classifications.  Ichnofossils, just like animals, have a classification scheme including genera and species.  However, because we don’t know what animals made the traces, we have to classify them based on similar appearance, rather than makers.  An article published in a 2012 edition of The Open Paleontology Journal explored the research of scientists trying to connect the burrowing habits of a particular sea cucumber to various types of fossilized burrows.  Although they were not exactly able to target a specific type of ichnofossil caused by this sea cucumber’s burrowing, ichnologists have had success in identifying trilobite tracks.