Fossilized footprints give us a unique look at prehistoric life in ways that we can't always get from fossilized bones. Footprints represent the living creature, whereas bones represent its death. Did you know that we find more dinosaur footprints than bones? It's true. And I guess when you think about it it makes sense. A dinosaur can leave only one set of bones in its lifetime, but that same dinosaur can leave hundreds, thousands and perhaps millions of footprints before it dies. That is why we find more tracks than bones.So how are footprints preserved? Well, first the dinosaur must walk though mud, silt, clay and even volcanic ash that has the right consistency for a track to be formed. This sediment must be thin enough so that the dinosaurs weight causes the foot to sink in, but it must also be thick enough to prevent the sediment from falling back into the track and filling it again. Once the tracks are made, they need to remain undisturbed long enough for the sediment to dry and ultimately turned to stone.
Once the track has been formed, and the sediment has been turned to stone, we have a world of information that can give us clues into the behaviors of dinosaurs. Tracks can tell us how large the dinosaurs was, what family group it belonged to, what direction it was traveling, if it was alone or in a group, and they can even give us an estimate of the speed that the dinosaur was traveling. Most of this information cannot be gathered by bones. Remember, tracks represent the living dinosaur, and bones represent its death!
Although tracks give us some great insight into the dinosaur, the tracks do not tell us for certain "who" left them. But there are ways we can guess at who left the tracks. First we look at the size and shape of the track. That gives us a good idea as to the family of dinosaurs it belongs to. Different kinds of dinosaurs have different kinds of feet. For instance, Triceratops has a completely different foot than T-rex. And Edmontosaurus feet are totally different than the foot of a long necked sauropod, like Diplodocus. So figuring out what "family" the dinosaur track belongs too is sort of easy. But then trying to determine the exact species is more difficult. So in order to try and figure it out, we turn to fossilized bones!
We look at all of the different kinds of dinosaur species that have been in the same area or rock formation where we find the tracks. Once we figure out what species lived in that area, we can begin to narrow it down. So in other words, if we find a great big three toed dinosaur track in Cretaceous rock in Texas, then chances are pretty good that it could be Acrocanthosaurus! We cannot be absolutely sure that we have identified the right dinosaur, but at least we know that we are close!
