Kangaroo: Escaping predators
The development of the kangaroos may be related to Australia's continuing drift northwards and the consequent drying and warming of its climate. This would have caused a reduction in forest cover and replacement by grasslands. Living in an open grassland would require that the herbivores feeding on the grass an ability to escape predators. In kangaroos the hind legs have become enormously powerful and the long muscular tail is held out stiffly behind to acts as a counterbalance which gives the animals a potential to reach speeds of 60 kph and to clear fences nearly 3 metres high.