The curse of zombie fossils
New research has revealed how the history of life can be distorted by the ways animals decompose and lose body parts as they decay - and the ways in which decayed bodies ultimately become fossilised.
Geologists have followed a macabre, and nasally-challenging road to knowledge, watching carefully as animal carcasses decompose in order to better understand the process. The study highlights the importance of understanding how a fossil is formed before trying to reconstruct it - and how the processes of decay that lead to loss of body parts interact with the processes that cause them to become preserved and fossilised.
Understanding how much of a fossil is missing, and what has been changed by decay and fossilisation, helps to create a more accurate picture of ancient animals and ecosystems. This is particularly important for things lacking hard skeletons and shells – including crucial fossil evidence of early animal life on Earth.
“As soon as an organism dies, it starts to decay, and this process of decomposition inevitably involves changes in how features or body parts look: they may collapse, alter their shape or position; all too soon they liquefy and are eaten by bacteria until nothing remains,” says Professor Sarah Gabbott from our School of Geography, Geology and the Environment.
Professor Mark Purnell, lead author of the study adds: “The more a body deteriorates over time, the more body-parts are missing - rather like modern representations of zombies in Game of Thrones and The Walking Dead.
“One consequence of this decay is that palaeontologists have to work with incomplete fossils. Some of the features that are present don't look anything like they did when the animal was alive, and many features are missing completely. The trick is to be able to recognise partially-decomposed features, and where body parts have rotted away completely.”