3. Ecological preservational bias

Many theropods would have been opportunistic scavengers as well as hunters.
They would favour environments, such as sea margins and lagoon shores, where carrion is abundant. These environments are conducive to fossilisation.
Many herbivores would favour dryer plains, offering less likelihood of fossilisation.
In some formations, theropods are the only known dinosaurs:
- Solnhofen (three theropods)
- Santana (four theropods)

Many theropods would have been opportunistic scavengers as well as hunters.