The story of the rise of the mammals is the research focus of a remarkable number of studies at the moment, and it turns out that it’s far more complex and fascinating than we thought. It’s long been thought that mammals began to take over the world as soon as the non-avian dinosaurs bit the asteroid-based bullet, but it turns out that the lumbering reptiles were in decline 50 million years before the spaceborne apocalypse arrived, and an earlier rise in the number of opportunistic mammals may be to blame.
Another study revealed that 93 percent of mammals died out alongside their dinosaurian neighbors at the time of the 66-million-year-old mass extinction event, but that they may have recovered their numbers within no more than 300,000 years – a remarkably quick time considering how the world’s climate had changed so rapidly and dramatically.
This new piece of research highlights that, despite all these twists, our basic narrative of how mammals came to rule the surface of the world is essentially true. With huge ecological niches left absent by the disappearance of habitat-dominating dinosaurs, they were free to spread across the world, multiply, and dominate.
Placental mammals are one of the three living subgroups of mammals, and include many different animals, such as orangutans, pictured here. tristan tan/Shutterstock