the remains or impression of a prehistoric organism preserved in petrified form or as a mold or cast in rock.
Fossils are evidence of past life. They are instrumental to our understanding of how plants and animals evolved and became extinct. That’s why fossils are such an important part of the paleontological work we do at the museum.
There are different types of fossils. Body fossils are the bones, shells, and teeth that have survived a long burial in the earth. Trace fossils are the marks the animals left behind, like dinosaur tracks or even their dung (those are called “coprolites” in earth sciences terms).
But one question often asked is … are dinosaur body fossils actually the real bone or are have those bones been changed into rock?
The surprising answer is: They are real bones.
Bones and teeth are each made of two main ingredients, a flexible material called collagen and a rigid mineral called hydroxyapatite. After an animal dies and its muscles and skin rot away, the very durable bones and teeth can last for thousands or even millions of years.
Even though they’ve lasted so long preserved in rocks and mountains and river beds, dinosaur bones are quite fragile. That’s why museums often put a replica of the original bone on display. There are two steps to this process. A mold is the material built around the original fossil. A cast is a copy of the original fossil made from the mold.
Another option that is becoming more common is to digitally print a fossil. This is done by first scanning the three-dimensional shape of a fossil with a laser or using photographs and then printing the fossil in plastic. A 3D-printed fossil can be viewed by researchers and experts anywhere in the world while the precious specimen stays safely preserved in the museum’s collections.
In the special exhibit Expedition Alaska: Dinosaurs opening May 23 at the UA Museum of the North, both real fossils and replicas will be on display. Some of them will even touchable!