31/10/2024
The first marsupial fossils ever found were in China (in the time of the dinosaurs). Placental mammals either didn’t arrive in Australia or they didn’t survive the harsh conditions in the polar regions during & after the dinosaur extinction (perhaps having very small but easily replaceable young gave them an advantage).
After Australia separated, forests turned into grasslands and possums came down from the trees & evolved into kangaroos. The grasslands spread and with an elasticity to the legs & a counterbalance of the tail, large kangaroos developed the ability to move rapidly that required little muscle movement (many times more efficient than any running placental mammal).
Agile Wallaby, Notamacropus agilis.