Australian paleontologists have discovered a new species of koala that lived in rainforests of northern Australia some 20 million years ago.

The discovery, reported in the Journal of Systematic Palaeontology, brings the number of known prehistoric species of koala to eighteen. Today, only one species of koala (Phascolarctos cinereus) is alive.

The new koala species was named Litokoala dicksmithi in honor of the Australian political activist, aviator, entrepreneur and philanthropist Dick Smith.

“We chose the name to thank Mr Smith for his long-term financial support of Australian science, in particular, of fossil research at the Riversleigh World Heritage Area in north western Queensland,” explained lead author Dr Karen Black from the University of New South Wales.

Litokoala dicksmithi was only about a third of the size of modern koalas, weighing in at about 3 to 4 kg.

“The discovery of Litokoala dicksmithi is particularly significant because it is one of only two fossil koala species that are known from material preserving the facial region including the snout.”

“The other species, called Nimiokoala greystanesi, which was also discovered at Riversleigh, had a skull that was very possum-like in appearance. Litokoala dicksmithi, however, appears to have been much more closely related to the modern koala with numerous similarities in the skull suggesting a more koala-like, rather than possum-like, face.”

“An interesting feature of the Litokoala skull is the extremely large eye sockets which suggest the intriguing possibility that these koalas were nocturnal with greater visual acuity than the living koala,” Dr Black said.

“Combined with its small body size, this suggests that Litokoala dicksmithi was a more active, agile tree climber than its sleepy, relatively sedentary, cousin that we know. Unlike today’s eucalypt-munching koala species, Litokoala dicksmithi fed on the rainforest plants that covered much of northern Australia 20 million years ago and may also have eaten some fruit.”

“The onset of dryer conditions in Australia about 15 million years ago led to the contraction of rainforest habitats and the apparent extinction of many koala species including Litokoala dicksmithi.”

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Bibliographic information: Karen H. Black et al. Understanding morphological variation in the extant koala as a framework for identification of species boundaries in extinct koalas (Phascolarctidae; Marsupialia). Journal of Systematic Palaeontology, published online May 14, 2013; doi: 10.1080/14772019.2013.768304