ScienceDaily has a story about the top predators of the past. Researchers from McGill University looked at Colombia’s Paja Formation, which dates to the early Cretaceous Period, some 122 million years ago. That formation preserves the ancient marine ecosystem, which had a very complex food chain, more so than the modern oceans. The paper was published in the journal Zoological Journal of the Linnean Society.

Trophic levels describe an organism’s position in a food chain based on how it gets energy and nutrients. Put simply, they explain who eats whom within an ecosystem. In today’s oceans, food chains typically reach only six levels, with animals such as killer whales and great white sharks sitting at the top.

The discovery of predators operating at a seventh trophic level highlights just how rich and complex the Paja ecosystem once was. It also offers rare insight into a deep evolutionary struggle, where predators and prey continuously adapted in response to one another.

To uncover this ancient food web, McGill researchers analyzed all known animal fossils from a single geological formation in central Colombia. They built a detailed ecological network using fossil body sizes, feeding traits, and comparisons with modern animals that fill similar roles today.