Colombian fossils point to evolutionary turnover without mass extinction

Discussed by: The McGill and CIP authors, who explicitly frame the paper as a testable model rather than a one-off description

Other research groups apply the term to their own fossil formations. The clearest candidates are the mammal turnover across the Paleocene-Eocene Thermal Maximum and the Great American Biotic Interchange, both of which the review itself names as possible matches. If several independent teams find the same relic-plus-novel overlap, the term stops being a label for one Colombian deposit and becomes a category of evolutionary transition.

Discussed by: Skeptics implied by the authors' own caveats, which state the formation cannot yet be called a paleohotspot under strict criteria

The Paja Formation is exceptionally preserved, and that may be the whole story. If comparable deposits elsewhere do not show relic and novel lineages overlapping, the pattern reads as a sampling artifact of one unusually rich site rather than a general mode of evolutionary change. The term then survives mainly in reviews of Colombian Cretaceous paleontology.

Discussed by: The authors, who list more accurate fossil ages as a prerequisite for testing the idea

The claim rests on relic and novel lineages actually sharing the same window of time. Tighter radiometric or biostratigraphic dating could show the two groups were separated by more time than the current stratigraphy suggests, which would dissolve the overlap. The authors name improved age estimates as one of three things needed to settle the question.