Billions of dinosaur tracks are found around the world. The most common tracks are the three-toed theropod tracks similar to the one shown above.
If you happen to be a hunter, and were hunting dinosaurs, you would need to know what type of dinosaur made the tracks you were following. A theropod could make a quick meal of you.
Another type of three-toed track is made by an ornithischian dinosaur. They are herbivores and a less likely to take a bite out of you.
These two types of dinosaurs left similar tracks, but you can tell which is which, if you know what to look for.
Theropod: Long Center Toe
The first thing you probably noticed is the center toe. Theropod footprint impressions often have a center toe that is significantly longer than the toes on either side.
Second, notice the toes on either side are close in to the foot. The foot impression is noticeably longer than wide.
I know I said this before, but keep in mind that dinosaur footprints are made by a living animal in a medium (mud in this case) that can vary greatly. That means foot impressions vary greatly, and that means some theropod footprints will not have these characteristics. What we are looking for is what a preponderance of the evidence points toward.
Theropod: Side Toe & Claws
Another characteristics of a theropod footprint is that the inside toe appears to be attached to the side of the foot, while the other toe goes all of the way back to the heel.
A fourth characteristic is that theropods have larger and more distinct claws. Ornithopods (herbivores) typically leave small claw impressions. For both types of dinosaurs the claws tend to make the deepest impression. When the footprint is faint, the claw impressions often will be the easiest part of the footprint to spot. So when searching for fossil dinosaur footprints, first look for the claw impressions. We'll talk about this in more detail shortly.
Theropods: Living Animals
These are the four key characteristics that distinguish a theropod footprint (carnivore) from an ornithopod footprint (herbivore).
These are not hard and fast rules. Dinosaurs are living animals. They'll move their feet in different ways as they walk, so each step can be slightly different. In addition, mud is a dynamic medium that takes on impressions in different ways depending on the characteristics of the mud. At times theropod footprints do not have all four, or even any of these characteristics. A dinosaur trackway (a trail of footprints made by a single dinosaur) may start out looking like theropod tracks, and then suddenly several tracks later they look like ornithopod tracks. Did the dinosaur suddenly morph into a different dinosaur? No. The way the foot was placed and/or the character of the mud changed. When all four characteristics are present you can be confident you are looking at a theropod footprint. However, at times it may be difficult to positively identify what type of dinosaur left a certain footprint.