When most organisms die, they biodegrade and leave little behind. But if they get trapped in sediments that harbor few bacteria and loads of dissolved minerals, they can become fossilized and preserved for millions of years. Scientists use a variety of techniques on the ancient specimens to determine details about lifestyles and diets, as well as information about the geographical distribution of the creatures. One of those methods called scanning electron microscopy, or SEM, showed particular promise for revealing new information about fossils. So Amauri J. Paula and colleagues expanded on this method.

Scientists pieced together 3,600 tiny images of this shrimp fossil to understand the processes that preserved it.
Credit: American Chemical Society

The researchers used a large-field SEM approach to analyze a shrimp fossil from the Araripe Basin, a place in northeastern Brazil known among paleontologists as a treasure trove of flying pterosaur remains. The shrimp specimen dates back to the Cretaceous period, when dinosaurs still roamed the planet. The technique provided evidence for the first time that a rare fossilization process occurred in the basin. It also showed that the fossil over millions of years developed a surprising fractal characteristic — a still-unexplained, repeating pattern most commonly recognized in snowflakes but also found in structures as large as spiral galaxies.