How Do Fossils Form?

What kid hasn’t been fascinated with dinosaurs at one point or another? Thanks to the fossil record, we’re in a unique position to be able to look back in time at creatures that, unless we recreate a few sci-fi movies, will never walk among us again. Without the process of fossilization, we wouldn’t know about the incredible history of the Earth and the strange creatures, both large and small, that once called our home their home as well. Here’s how all those brilliant fossils formed.

1. Location, location, location.
It might not seem like it given the number of dinosaur bones we’ve found over the years, but the vast majority of animals and plants do not become fossils. The process requires very specific steps, and the first one involves where the animal dies. Muddy, watery locations are best for preservation.

2. When they’re in the right location, petrification occurs.
If an animal dies in the prime location, the next steps aren’t too difficult to achieve. First, the soft tissues are eaten or rot away. That leaves behind the bone, which gets covered in sediment like mud and silt. Over long periods of time, the sediment continues to build up, putting pressure on the lower layers. With enough pressure, these layers can turn to rock. While the mud is turning to rock, the animal bones are saturated with water, which leaves behind minerals. These minerals turn into stone, and as a result they form a pristine recreation of the bone.

3. There are a few other methods of fossilization.
Petrification is just one method of fossilization. Other methods include natural casts (when minerals fill a mold in the shape of the creature or bone), amber preservation (the animal is trapped in amber), trace fossils (such as footprints), and preserved remains (such as those buried at Pompeii).