Planet Earth

Drying Climate Turned Possum-Like Critter Into the Strange Koala

80beatsBy Andrew MosemanDec 23, 2009 9:15 PM
koala.jpg

Newsletter

Sign up for our email newsletter for the latest science news
 

Millions of years ago, a koala looked more like a possum. By studying rare skulls of the famous marsupial that date between 5 and 24 million years old, a team of Australian researchers propose how it got to looking like it does today, with findings published in the Journal of Vertebrate Paleontology. Food was one driver, they say—millions of years ago koalas ate a variety of foods.

The dietary switch to an exclusive eucalypt diet seems to have occurred during the late Miocene period, some 12 to five million years ago, when a drying climate made eucalyptus the dominant forest species [Canberra Times]

. As a result, they lost their snouts and developed powerful jaw muscles. But while koalas need to adapt to the changing food supply, they also needed to stay in communication, and began to develop the low-frequency calls that today can travel half a mile.

The researchers hypothesize that the ancient koalas evolved their communication system at a time when the Australian continent was drying out and the koala habitat becoming less dense. By lowering the frequency of their calls, they were able to maintain communication in the sparser forests [Wired.com]

. And to hear those low-frequency calls, koalas developed a middle ear with high volume compared to other marsupials.

“The unique cranial configuration of the modern koala is therefore the result of accommodating their masticatory adaptations without compromising their auditory system,” write the researchers [Wired.com]

. In other words: you put those two things together and you get today's adorable but strange marsupial. Related Content: 80beats: Worsening Drought Threatens Australia's "Food Bowl" Discoblog: Rat Risotto And Emu Chips: Thing Not To Eat in Australia DISCOVER: One Marsupial Too Many

Image: flickr / tinyfroglet

1 free article left
Want More? Get unlimited access for as low as $1.99/month

Already a subscriber?

Register or Log In

1 free articleSubscribe
Magazine Examples
Want more?

Keep reading for as low as $1.99!

Subscribe

Already a subscriber?

Register or Log In

More From Discover
Recommendations From Our Store
Shop Now
Stay Curious
Join
Our List

Sign up for our weekly science updates.

 
Subscribe
To The Magazine

Save up to 70% off the cover price when you subscribe to Discover magazine.

Copyright © 2021 Kalmbach Media Co.