A lone dinosaur bone in Utah's Grand Staircase-Escalante National Monument.
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Photo by Brian Switek.
A lone dinosaur bone in Utah's Grand Staircase-Escalante National Monument.

Petrified Afterlives

When I was a young fossil fan of about nine, my favorite book was David Norman’s Illustrated Encyclopedia of Dinosaurs. The local librarians must have wished that I’d just buy a copy instead of checking it out at least once a month. But I couldn’t help it. The book was dense with information and imagery, with a menacing menagerie of scaly dinosaurs brought to life by artist John Sibbick. Every time I rifled through the pages I was struck by something I had never thought about before.

I was especially transfixed by a small inset in the introduction titled “Fossilization”. The small diagram followed five steps for turning a living animal into a pile of bones ready for excavation – death, decay, burial, mineralization, and exposure. Simple enough. But what fascinated me was what the explanation left out. Even though the image showed a perfectly-articulated sauropod, I had learned that most dinosaurs wound up as partial skeletons or fragments – the “chunkosaurus” that would later taunt me as I got the chance to search for dinosaurs myself. What conditions made the difference between a dinosaur that looked like it died in its sleep and a pile of sun-bleached bone shards?

Eventually I learned that there’s an entire branch of paleontology devoted to such questions. It’s called taphonomy – an area of ancient investigation lecturers frequently sum up as “what happens to an organism between death and discovery“. The discipline seeks to draw out the hidden history of fossils by tracing what time has done to expired life.

In order to figure out why an organism perished and how chance preserved it, though, taphonomists must turn to current conditions. The present is the key to the past, as every devotee of Deep Time knows, and sometimes that means meticulously documenting the afterlives of little dead crocodiles. That’s just what paleontologist Caitlin Syme did, and she was kind enough to talk to me about the experiment at the last Society of Vertebrate Paleontology meeting in Berlin: