Mammals are evolved from mammal-like reptiles. Thanks to its advantageous constant body temperature and the wet, warm and humid climate conditions in the Mesozoic era, the mammals have enjoyed great development. The exhibition hall describes in detail the evolution of the proboscideans, the perissodactylas, the Artiodactylas, the carnivores, the primates and the angiosperms as well as the famous Mountain-Wang Biota. In the exhibition hall, the audience can see the reconstruction drawings and teeth and bone fossils of the bemalambda which is the largest mammal on the planet over the same period when dinosaurs extinguished; and they can have a look at the a huge elephant family, including the famous 4-meter-high 8-meter-long Huanghe River stegodon and the platybelodon. Moreover, the audience can find a very eye-catching specimen – the Archaefructus liaoningensis Sun et al. which is the world's first flower.