Paleontology

Paleontology investigates the biology of life in the geological past. Its evidence includes more than skeletons: fossils can be body remains such as bones, shells, leaves, and wood, or traces of activity such as footprints, burrows, eggs, and fossilized waste. The field ranges from microscopic fossils to plants and large animals, and asks how organisms were structured, where they lived, how they related to other forms of life, and how ecosystems changed. Paleontology therefore draws on both biological questions and the geological record in which fossils are preserved.

Fossilization is a set of processes rather than a single route. Rapid burial in mud, sand, or silt can protect remains from ordinary decay; over time, minerals may replace or fill parts of the material. Other conditions can preserve impressions or traces, and some organic remains survive in substances such as amber or tar. Which details are preserved depends on the organism and what happens after it dies. As a result, the fossils available to study are a selective record of past life, not a complete census of everything that lived.

A fossil's position and relationship to the surrounding rock are part of the evidence. During fieldwork, paleontologists record a find's location and geological context so that later researchers can interpret it rather than treating it as an isolated object. Many fossils occur in sedimentary rocks, formed as particles settle in layers and are compacted. In an undisturbed sequence, lower layers are generally older than those above them; comparing rock layers and their fossil contents helps geologists establish relative ages and correlate strata from different places. Such work links the study of ancient organisms with stratigraphy and historical geology.

By comparing fossils with one another and with living organisms, researchers investigate biological form, evolutionary relationships, geographic distribution, extinction, and past environments. Fossils can also help identify and compare sedimentary rock strata, so paleontological evidence contributes to reconstructions of Earth's history as well as the history of life. Paleontology is distinct from archaeology: archaeology primarily studies past human history and culture through material remains, while paleontology uses fossils to investigate organisms and life in geological time. Museums and research institutions curate fossil collections so specimens can be examined and compared by researchers over time.