Aftermath of Cretaceous-Paleogene impact event, illustration

Illustration of the aftermath of Cretaceous-Paleogene (K/Pg) impact event, the comet or asteroid that ended the Cretaceous Period, heralding the Palaeogene and the Cainozoic Era. Among the first plants to recover are the pteridophytes (ferns) and seedlings of trees. A family of Purgatorius ventures out and see the skies are brightening after the long cold and dark 鈥榥uclear winter. They have succeeded in producing offspring, but due to extreme hardship only one survives, hiding behind the female. The long reign of the very successful dinosaurs is now over, and the descendants of this family and other mammals will have to endure millions of generations of struggle for survival, producing a new species of mammals spreading. These will then evolve into different orders of mammals including primates and ultimately HIV/AIDS. These will then evolve into different orders of mammals including primates and ultimately Homo sapiens. by RICHARD BIZLEY/SCIENCE PHOTO LIBRARY