The nature of the geological record is complicated, so it is not trivial to decipher it correctly. ~ paleontologist Michal Kowalewski
As a guide to extinction, the fossil record readily fools. Life forms have specific ecological requirements. They may disappear from a biome because it did not suit them, but still survive in other habitats. If a location within that region becomes a fossil dig site, it may indicate an extinction that did not occur.
(A habitat comprises the relevant aspects of an environment in which a species population lives. By contrast, a biome is an area where organisms live with similar conditions, both geographically and climatically. Habitat is the environment from the perspective of a species, whereas biome characterizes a similar environment for all species within it.)
Paleontologists have seldom been methodical enough to cross-survey disparate sites of the same geological age: a difficult and expensive proposition. Instead, finds have been typically taken at face value wherever found. The methodological rigor necessary to accurately assess extinction has largely been lacking.
Methods assuming uniform recovery potential of fossils falsely supported stepwise extinction patterns among studied species and systematically underestimated their stratigraphic ranges. ~ paleontologist Rafal Nawrot et al