In
paleontology,
biochronology is the correlation in time of biological events using
fossils. In its strict sense, it refers to the use of assemblages of fossils that are not tied to stratigraphic sections (in contrast to
biostratigraphy, where they are). Collections of land mammal ages have been defined for every continent except
Antarctica, and most are correlated with each other indirectly through known evolutionary lineages. A combination of
argon–argon dating and
magnetic stratigraphy allows a direct temporal comparison of terrestrial events with
climate change and
mass extinctions.