Riversleigh Fossils – World Heritage

This site is dedicated to information about the Riversleigh World Heritage Fossil site in remote north west Queensland in the tropics of Australia. The current page gives a very brief summary of the significance of Riversleigh, while we develop more pages of information and links.

Riversleigh covers an area of approximately 80 square kilometres and is located 250 km north-west of Mt Isa. The fossils document the evolution and changes of Australia’s terrestrial fauna and ecosystems.

Riversleigh from the air

Riversleigh limestone outcrops from the air

Riversleigh is one of the world’s richest Oligo-Miocene mammal records, linking that period (15-25 million years ago) to the predominantly modern assemblages of the Pliocene and Pleistocene epochs. The site provides exceptional examples of middle to late Tertiary mammal assemblages, in a continent whose mammalian evolutionary history has been the most isolated and most distinctive in the world.

The extensive fossil deposits at Riversleigh are encased in hard, rough limestone, which was formed in lime-rich freshwater pools. They span a record of mammal evolution of at least 20 million years in length, providing the first records for many distinctive groups of living mammals, such as marsupial moles and feather-tailed possums, as well as many other unique and now extinct Australian mammals such as ‘marsupial lions’.

The variety of deposits at Riversleigh has led to an understanding of how the environment has changed over time from a rich rainforest community to semi-arid grassland, and how the animals that lived in it have changed too.

The discovery of the fossils at Riversleigh has profoundly altered the understanding of Australia’s mid-Cainozoic vertebrate diversity. The remains of a 15 million-year-old monotreme has provided new information about this highly distinctive group of mammals, and several Tertiary thylacines have been identified. Placental mammals are represented by more than 35 bat species and the Riversleigh fossil bat record is the richest in the world.

Vast arrays of often exquisitely preserved marsupial fossils dominate the assemblages. These include species long extinct, such as:

carnivorous kangaroos,
marsupial moles,
primitive koalas and wombats,
huge crocodiles,
gigantic flightless birds,
a range of ancestral thylacines (Tasmanian tigers),
ancestral platypus (representing monotremes),
rodents (representing placental mammals),
small lizards and beetles, and
more than 40 different bat species, making Riversleigh one of the richest bat sites in the world.
“Only in one or two places on the surface of our planet, in the course of the last three thousand million years, have conditions been just right to preserve anything like a representative sample of the species living at any particular time. Those places are the rare treasure houses of palaeontology. Riversleigh is one of them.”
Sir David Attenborough.

Since 1983, the preserved remains of thousands of ancient inhabitants of northern Australia have been recovered from Riversleigh. Almost half of what we know about the evolution of Australian mammals in the last 30 million years comes from bones found at a single site in the Riversleigh fossil beds. Amazingly half of these bones were unearthed in one hour.
Diprotodon – Image source Riversleigh Centre, Mt Isa
Diprotodon: this sheep-sized herbivorous animal was the largest marsupial known from anywhere in the world.