The mass extinction that wiped out dinosaurs and other life 65 million years ago apparently did not, contrary to conventional wisdom, immediately clear the way for the rise of today’s mammals.

In fact, the ancestral branches of most mammals, including primates, rodents and hoofed animals, emerged long before the global extinction and survived it more or less intact. But it was not until at least 10 million to 15 million years afterward that the lineages of living mammals began to flourish in number and diversity.