Don’t pooh-pooh this job until your understand it
If you had told 18-year-old me that I would one day be an ichnologist, I wouldn’t have believed you – or even known what that was. But, more than 15 years later, I am an ichnologist.
Ichnology is the study of the tracks and traces made by animals and plants in the fossil record, also called trace fossils.
These can range from animal footprints, invertebrate trails, feeding traces on fossil leaves, fossilised faeces (coprolites), tooth traces (gnaw and bite marks) on bone and wood, to burrows and borings, all preserved in the sedimentary rock record.
When someone mentions seeing a “dinosaur footprint” they are talking about ichnology.
Looking at fossils doesn’t just help scientists understand animals and plants that existed long ago: it also informs our understanding of the environments they occupied and other aspects of the past world like extinction events or climate change.
That can help us understand how things might shift in future.
My current work deals with fossil footprints (tracks) of one of the largest animals to have walked the earth: the sauropod.
These dinosaurs of the Jurassic and Cretaceous periods (~200 and 150 million years ago) are like nothing we know today.
Our knowledge about sauropods is collated from their body and trace fossil records.
Sauropod tracks tell us the morphology of the feet, anatomical details, such as toes and claws, and occasionally with exceptional preservation, the texture of the skin via skin impressions.
Tracks can reveal how the animal gripped the substrate as it walked, how fast it was moving, or simply show that it was there, especially if no body fossils are available .
In northern Zimbabwe, for example, sauropod body fossils are rare but their tracks have been found and indicate enormous animals with feet 94cm long and 54cm wide. By comparison, an African elephant has a footprint length of 30cm to 40 cm.
A fossil burrow is another type of trace fossil and provides evidence for the excavation of a dwelling, a refuge, or even a trap for prey (to name a few).
SA’s Karoo Basin preserves some of the world’s finest and most unusual fossil burrows.
While the idea of fossilised faeces might gross you out, coprolites reveal what that animal ate and may preserve in it fragments of fossil. Collectively, this evidence helps to paint a picture of long-gone landscapes and the creatures and plants in them.
Ichnology often requires a good understanding of biological and abiotic (related to the sedimentary processes that lead to preservation) processes in geology, zoology and botany – as well as in chemistry, physics, and maths.