Fossils are the remains and traces of ancient, once-living organisms. To qualify as a fossil, an organism usually must be more than 10,000 years old. Out of all the millions of species that have evolved and lived on this planet since life first began 3.9 billion years ago, very few have been preserved as fossils.
There are many types of fossilization. Organisms with hard parts, such as bones, scales, teeth, or shells, are better documented in the fossil record because they are more likely to fossilize. Soft body parts, such as skin, muscle tissue, and organs, decompose rapidly and are often consumed by predators before fossilization can take place.
Replacement, or petrification, occurs when the original material (bone, shell, organic plant matter) is replaced by minerals. The original plant material of this Cunninghamia cone was replaced during fossilization by silica, a common quartz mineral. This specimen was discovered in an ironstone bed in Midland Provincial Park near the Museum.
Once buried, minerals carried in ground water may be deposited in the empty spaces within plant or animal matter, resulting in permineralization. This type of fossilization often shows incredible detail, like the microstructure of bones. One of the best ways to determine how old a dinosaur was when it died is to take a cross section of a limb. Thin slices were removed from this hadrosaur tibia, and then examined under a microscope. Researchers have determined that this hadrosaur was three years old when it died.
When a plant or animal dies and is buried by sediment, hydrogen and oxygen are eliminated, resulting in a carbon etching. Plant leaves are often fossilized in this manner. This fern fossil was found by Museum staff at the Grassy Mountain Coal Mine, 7 km northeast of Blairmore, Alberta. It’s an excellent example of the exquisite plant fossils found in the area since the mine has been operating (on and off for nearly 100 years).
Molds and Casts
Natural molds occur when the original skeletal part dissolves, leaving an impression in the surrounding rock. A natural cast is created when mud or other material fills the mold. These tracks are from a large ornithopod, a bipedal, herbivorous dinosaur, and show that they had large fleshy pads beneath the bones of their feet.
Trace fossils, or ichnites, include the preserved traces, burrows, and tracks of once-living organisms. Fossil footprints provide important information about how animals moved, and interacted with their environments, and each other. These footprints reveal three small to medium-sized theropods walking on a mudflat and sinking up to their ankles.
In rare instances, fossils consist of the unchanged remains of organisms. Very cold temperatures can sometimes preserve specimens in an essentially unaltered state. Unlike typical fossils, this walnut from the Miocene Epoch has not been turned into stone.
Impressions of skin (and, in very rare circumstances, hair) can be preserved in rocks. A well-preserved hadrosaur was discovered at a Korite mine earlier this summer. The specimen contains a number of patches of preserved skin that our scientists are currently studying.
Amber is the fossilized resin, or sap, of ancient plants. Occasionally, plant or animal remains become trapped in the resin and are preserved, often in great detail. Feathers were found in several pieces of amber in our collection, representing both dinosaurs and birds. Several of the feathers demonstrate that some birds had adaptations for flight and underwater diving during the Late Cretaceous.