Microsites and Macroinferences

When you think of research on dinosaurs and other fossil vertebrates, most people picture quarries with a number of people digging up a single animal. But when trying to determine how dinosaurs fit into the larger ecological community, and how those communities changed over time, across landscapes, and in response to changing climate, individual skeletons may not suffice. That’s where microsites become useful.

Microsites, or vertebrate microfossil sites, are concentrations of small vertebrate fossils representing a paleocommunity from a small time interval. They are formed in low energy ponds and rivers, acting as sink for material from the region. These sites can be identified in the field by looking for small teeth, bones, and scales eroding out together across an outcrop. Once identified, the site can be surface collected (picking up the visible material), and it can be bulk sampled. Bulk sampling involves filling dozens of bags full of the sediment from a microsite, and then screen-washing all of that material to concentrate the fossils and separate them from the rock

What is so interesting and important about them is that they provide a snapshot of the ecological community of a given area, generally preserve both the species that we find as skeletons as well as the remains of many species that would otherwise be unknown and provide sample sizes large enough to perform statistical analyses within and between sites to test ecological hypotheses. When we take all of these features together, and then combine them with environmental data obtained from the rock record, we can start to really understand how vertebrate communities (including dinosaurs) responded to climate change and which habitats they preferred. Building up a microsite database that includes many different sites can be a long and labour-intensive process, but it is well worth it when the reward is understanding how the dinosaurs lived and interacted with their world.