In Colombia's fossil seas, old and new worlds of life overlapped — and evolution changed without a catastrophe

Textbooks often tell evolution as a story of disasters: an asteroid falls, the old world ends, a new one begins. The Paja Formation near Villa de Leyva in central Colombia tells a gentler story. McGill University and Colombian palaeontologists studied its Early Cretaceous marine ecosystem — giant long-necked plesiosaurs, marine crocodile relatives, turtles and sharks preserved together — and found lineages on the brink of disappearing living alongside newcomers that would later flourish. They call the pattern a 'biotic inflection': a great turning of life that needed no mass extinction to happen. The findings are published in Frontiers in Ecology and Evolution.