“For the first time in years, the sun broke through the darkness.”
A couple of years back, I read Steve Brusatte’s excellent book about the age of the dinosaurs. I was delighted that he decided to carry on in time and cover the mammals.
From humble beginnings to world domination, the story of the mammals looks like your standard “rags to riches” tale, but it is anything but. Our mammalian ancestors have been around since the dawn of the dinosaurs, but rarely had the chance to get very big, especially once the reptiles had taken over, and it was only the falling of an asteroid around 66 million years ago that allowed them to begin their true rise to power.
There have been ups and downs, as the book explains, but mammals have somehow always held on, usually in a small, rodent-like form, but not always. Monotremes and marsupials were once far more common than today, but it is the placentals that managed to spread successfully around the world, leaving the others to the southern hemisphere, in particular Australia. Although the evolution of humans is discussed in the book, we are but one branch on this enormous, sprawling family tree.
Along the way we meet familiar faces such as the woolly mammoth, the sabre-toothed cat, and even the ancient Dimetrodon, which is often mistaken for a dinosaur but is more closely related to us. These were definitely the sections I found easier to comprehend, because, unlike the dinosaurs, a lot of the prehistoric mammals are less well known. They are nonetheless fascinating. The chalicotheres are favourites of mine, which were giant horse relatives that walked on their knuckles like gorillas, and then there are the South American Toxodon, a beast somewhere between a rhino, a manatee and a guinea pig. The past is a world where great birds prey on tiny horses, whales have legs, anteaters swarm through central Europe, and sloths are simply enormous.
Brusatte also spends a lot of time talking about his own discoveries, and those of his heroes, colleagues and students. There are a lot of examples of great work done by female palaeontologists too, which felt really pleasing, as the media would often suggest it’s one of those fields dominated by men. We find out about the fossils that Thomas Jefferson worked on, how we can tell what a creature ate by its teeth, and how camels and horses spread around the globe, despite both evolving in North America (but having to be reintroduced by humans later on). There are plenty of mysteries too. We don’t have the missing link between bats and non-flying mammals, for example, and we’re still not really sure what drove all the megafauna of the last glacial period of the Ice Age to extinction.
We’re never going to have a complete picture of what the past looked like, but this excellent book shines some lights on some surprising corners.