About 325 million years in the past, when Britain sat close to the equator as a part of the supercontinent Pangaea, two populations of a small, scaly, swamp-dwelling creature separated from one another. One among these lineages, over tens of millions and tens of millions of years, advanced into mammals. Our ancestors shared the planet with dinosaurs, survived an asteroid and made it via an ice age. This fascinating historical past is documented in The Rise and Reign of the Mammals, a brand new e book by the palaeontologist Prof Steve Brusatte. The Guardian science correspondent Nicola Davis talks to Madeleine Finlay about her go to with Brusatte and what she discovered concerning the unusual mammals that after walked the Earth. What may their previous reveal about their future in a quickly altering world?