Paleontologists have long believed that mammals won the battle of evolution almost by default from lack of opposition after the extinction of the dinosaurs. But discoveries made in China since the turn of the 21st century prove that our ancestors had prepared their weapons well before then. But how far back do the mammals’ key advantages go? For 10 years, the debate has raged between geneticists and paleontologists. Until the end of the twentieth century, our only knowledge of primitive mammals was based on isolated teeth or jaw fragments, but the Jurassic site of Liaoning has finally given access to complete and remarkably preserved fossils: Eomaia scansoria (2002), the ancestor of placental mammals, Repenomamus giganticus (2005) a mammal the size of a dog, as well as a type of gliding squirrel (Volaticotherium antiquus – 2006) and a mammal similar to the beaver (Castorocauda – 2006). The use of innovative technologies such as 3D scanners enable us to track the origin of our evolutionary assets: gestation, hair, teeth and hearing. Yet, despite these discoveries, a controversy still agitated the scientific community who were unable to agree on a family tree for our ancestors of the Mesozoic era! Two opposing teams displayed their disagreements through articles published in the scientific journal, Nature. The key question – when did placental mammals separate from marsupials? – remained unanswered. Until the discovery of “Juramaia sinensis”, Jurassic mother of China, which finally put an end to the long-running dispute between geneticists and paleontologists. This fossil extends our family tree back another 35 million years: an ancestor that lived nearly 160 million years ago….
