Predator/Prey Ratios

Does the larger amount of food needed by warm-blooded creatures effect the proportions of animal types in the community?

Living animal communities have been studied to find out the amounts of predatory animals (gl) and prey animals (gl) they contain. It was discovered that, in communities with warm blooded predatory animals, more prey animals were found.

Can we use predator/prey ratios to find out about dinosaur communities?

Some people think so and have calculated surprisingly low predator/prey ratios for dinosaur communities. This suggests dinosaurs were warm-blooded.

Click here to find out how predator/prey ratios are calulated

How accurate can you be when looking at dead (fossil) communities?

There are a lot of problems encountered when trying to bring a fossil community to life. Some particularly relevant for predator/prey ratios are:

The fossil record does not represent the whole community. Some animals will be missing and this can effect calculations. For example, younger and smaller animals are often not preserved. Also, people making dinosaur collections are more likely to pick well preserved or exciting specimens such as Tyrannosaurus Rex.
There are no cold-blooded predators as big as the dinosaurs alive today. This makes it hard to compare communities.
It has been suggested that when cold-blooded animals get as big as dinosaurs the predator/prey ratios may decrease becomming more like those of warm-blooded predators.
Other factors that we cannot measure for fossils today may also effect the ratios.For example:
-predator efficeincy
-size of prey
-structure of populations e.g. predators feeding selectively