As Hartenberger explains, what we know of the earliest mammals rests on discoveries of their fossil remains, and the further back you go, the less remains of those fossils. Recent discoveries in China, such as the Liaoning excavation and the Ukhaa Tolgod findings have offered up some of the most exciting large and more complete specimens of early mammals to date. Their discovery provided nothing less than a total rethinking of the diversity and quantity of early mammalian life. With charming black and white line drawings and diagrams (including the six most famous mammalian family trees of the past), this is a most accessible and elegant look at the way we explain our past, and how it shapes what we know today.