Mammals come in many shapes and sizes, from blue whales to pygmy shrews, and are able to live in a wide variety of habitats, from the polar regions to arid deserts and the open oceans. Archaeological and fossil mammal remains are usually found as either bones or teeth. Mammalian fossils are often divided into two groups – microfauna or small mammals and macrofauna or large mammals. The study of taphonomy has traditionally been focused on measuring and determining the loss of biological material as it becomes incorporated into the geological record. Taphonomic analyses can provide an important source of palaeoenvironmental information. The first point when considering palaeoenvironmental reconstruction from faunal remains is the identification of those remains to a taxonomic group. Autecology is the study of a single species, which can then be used to reconstruct environments. Body size is arguably the most important ecological attribute of any mammal.