Learn about the time period that took place 65 to 23 million years ago. 3 min read At the dawn of the Paleogene—the beginning of the Cenozoic era—dinosaurs, pterosaurs, and giant marine ...

Cretaceous-Paleogene (K-Pg) boundary: The geological boundary marking the end of the Cretaceous period and the beginning of the Paleogene period, characterized by a mass extinction event.