Australonycteris clarkae illustration Click to enlarge image
Australonycteris clarkae illustration Image: Dr Anne Musser
© Dr Anne Musser

Where is Murgon?

The Murgon Fossil Site is located near Kingaroy in south-east Queensland (26° 14' S, 151° 57' E).

Why is Murgon important?

The site is significant as the only site in Australia that records a diverse vertebrate fauna dating from the early Tertiary Period (55 million years ago), approximately ten million years after the extinction of the dinosaurs. The site includes some outstanding fossil records, including the world's oldest fossil songbirds, the oldest fossil marsupial remains in Australia, a placental mammal (Condylarth), one of the world's oldest bats, the only known fossil remains of leiopelmatid frogs, and the only known fossils of salamanders in Australia.

Fossil time period: Murgon

At the end of the Cretaceous Period, 65 million years ago, life on earth was affected by massive extinctions. Of the dinosaurs only a single lineage, the theropods, survived as modern birds. This gave mammals an opportunity to diversify and become a more successful form of vertebrate life. After 10 million years, in the Early Eocene epoch, mammals across the world were evolving into new and fascinating forms. The Australian continent was evolving too, still joined with Antarctica and South America as the supercontinent Gondwana. From the 54.6 million-year-old clays at Murgon comes evidence of this ancient association in the form of a unique assemblage of fossil animals.

Murgon fossils

Although discovered in the 1930s, it was in the 1980s when palaeontologists Henk Godthelp and Mike Archer recognised the significance of the lake sediments at Murgon in southeastern Queensland which yield Australia's oldest known Tertiary mammals. The ancient swampy environment was home to soft-shelled turtles, Australia's oldest known frogs and swamp crocodiles of the genus Kambara. Among the trees flew Australia's oldest known bat, Australonycteris clarkae, and birds that have been recognised as the world's earliest known songbirds, raising the possibility that this group of birds evolved in Australia.

The primitive, almost unrecognisable ancestors of Australia's modern mammal fauna are present such as Australia's oldest known bandicoot, a strange marsupial omnivore Thylacotinga bartholomaii, and several marsupial insectivores. Evidence of Australia's Gondwanan links with South America comes in the forms of fossils of Alamitophis sp., a madstoiid snake of the same kind as Patagonian forms and a microbiotheriid marsupial - microbiotheriids are a group of marsupials otherwise known only from South America.

One of the most significant finds from Murgon, confirming the Gondwanan connection was the discovery of the placental condylarth Tingamarra porterorum. This internationally significant fossil is Australia's oldest placental land mammal. Scientists once thought that non-flying placental mammals first colonised Australia in the Late Miocene/Early Pliocene when they first appear in the fossil record. However now it seems that both placentals and marsupials lived in Australia in the early Tertiary, although only marsupials persisted.