CretaceousPaleogene
Cretaceous-Paleogene, commonly abbreviated K-Pg, refers to the boundary between the Cretaceous and Paleogene periods about 66 million years ago, marking a major mass extinction event in Earth history. It is also known as the K-Pg boundary, replacing the older K-T terminology. The boundary is identified in the rock record by abrupt changes in fossil assemblages and a distinctive global stratigraphic layer.
The most widely supported cause is the impact of a large asteroid or comet, evidenced by the
Extinction was profound among many life forms, including non-avian dinosaurs, pterosaurs, many marine reptiles, ammonites, and
Stratigraphically, the boundary is a key marker layer worldwide, used to synchronize geological and paleontological records.