PERTH.- A Western Australian Museum-led study has discovered two new species of extinct kangaroos that lived in ancient Australian rainforests between 24 to 18 million years ago in northern Queensland.

Lead author Dr Kenny Travouillon, Curator of Mammalogy, said that these two new species were recovered from several fossil deposits at the Riversleigh World Heritage Area in northern-western Queensland. “Our analysis of the teeth and bones shows that these two new species (Gumardee springae and Gumardee richi) are related to bettongs and potoroos, members of the Rat-kangaroo family Potoroidae,” he said.

Gumardee springae lived about 24 million years ago, while Gumardee pascuali and Gumardee richi lived between 20 and 18 million years ago.

Dr Travouillon noted that like bettongs and potoroos, these new discoveries have a set of very long teeth (premolars) which bettongs and potoroos use to chew fungi, and they are closely related to a species named by Prof. Tim Flannery (Head of the Climate Council of Australia) in 1983 Gumardee pascuali, of which his team had since recovered more specimens. Bettongs and potoroos are quite small animals, weighing between 500g and 3.5kg, but the new species are a lot larger, estimated to weigh 4-6kg, hence the nickname ‘giant bettong’.”

The study is published in the Memoirs of Museum Victoria, Special issue in honour of Dr Thomas H Rich, along with another study on the diet and locomotion of ancient kangaroos which Dr Travouillon co-authored.

“In this second study, we have found that ancient kangaroos didn’t feed on grass like most kangaroos do today, but instead some ate leaves from trees and shrubs (browsers), while others ate a wide variety of foods (omnivore). One of the new species (Gumardee springae) was found to be predominantly a leaf eater.”

“We also found that some members of the ancient family of Fanged-kangaroos which was thought to be unable to hop were actually probably able to climb trees instead, while others hopped on the ground.”

This study is significant because it shows that at least twice kangaroos evolved the ability to climb trees, a feature for which they are not well-known. Today, there are several species of Tree-kangaroos, two living in the rainforests of north-eastern Queensland, and 10 others living in New Guinea and surrounding islands.

The full texts of Dr Travouillon’s studies can be found here.