For most of us, the story of mammal evolution starts after the asteroid impact that killed the dinosaurs, but over the last 20 years scientists have uncovered remarkable fossils and new technologies that have upended this story. In Beasts Before Us , palaeontologist Elsa Panciroli charts the emergence of the mammal lineage, the Synapsida, beginning with their murky split from the reptiles in the Carboniferous period, more than three-hundred million years ago; these animals made the world theirs long before the rise of dinosaurs. Travelling forward into the Permian and then Triassic periods, we learn how our ancient mammal ancestors evolved from large, hairy beasts with fast metabolisms to exploit miniaturisation, the key to unlocking the traits that define mammals as we now know them. Elsa criss-crosses the globe to explore the sites where discoveries are being made and to meet the people who make them. In Scotland, she traverses the desert dunes of prehistoric Moray, where quarry workers unearthed the footprints of Permian synapsids; in South Africa, she introduces us to animals that gave scientists the first hints that our furry kin evolved from a lineage of egg-laying burrowers; and in China, new and astounding fossil finds reveal a suite of ancient mammals including gliders, shovel-pawed moles, and flat-tailed swimmers. This brilliantly written book radically reframes the narrative of our mammalian ancestors, providing a counterpoint to the stereotype of cowering Mesozoic mammals hiding away from their mighty dinosaur overlords. The earliest mammals weren't just precursors – they were pioneers.