Australasian Science: Australia's authority on science since 1938

Kangaroo Teeth Tell Their Story of Evolution

By John Long

An analysis of kangaroo teeth reveals a rapid burst of evolution in response to the expansion of grassland rather than drier climate conditions.

The full text of this article can be purchased from Informit.

Kangaroos and wallabies are iconic Australian macropods with a reasonably good fossil record extending back at least 25 million years. The oldest kangaroos include small hopping forms like Ngamaroo archeri from the Lake Eyre Basin of South Australia. While it is clear that the group radiated into many lineages in the Miocene (23–25 million years) it has been unclear when the modern macropod fauna evolved and what environmental drivers directed their radiation.

A landmark paper published in Science in October (https://goo.gl/jUUB3f) has now demonstrated that modern kangaroos and some recently extinct short-faced forms called sthenurines underwent a rapid burst of evolution in the Pliocene 5–2.6 million years ago. The research by former PhD student Aidan Couzens and Gavin Prideaux, both of Flinders University, followed a new approach to the problem of how modern kangaroos evolved by looking at the teeth of living and fossil kangaroos.

Plant-eaters that eat a lot of grasses suffer increased dental abrasion due to the high silica content and adhering dust. The evolutionary response to this by kangaroos was to make the teeth taller, or higher-crowned, increasing the durability of their teeth.

Kangaroos also responded to the aridification in a slightly different way than the herbivores...

The full text of this article can be purchased from Informit.