20 million years ago - Australia's splendid isolation
The bones speak
Thousands upon thousands of fossil bones have been recovered from the limestone at Riversleigh. Study of these fossils continues, but the sheer number of different kinds recognised reveals a lost kingdom far more diverse than any found in Australia today.
Among the many kinds already identified are:
- Freshwater snails: at least three kinds
- Frogs: at least 20 kinds
- Snakes: at least four kinds
- Crocodiles: nine kinds
- Turtles: 20 kinds
- Birds: at least 12 kinds
- Bandicoots: at least nine kinds
- Thylacines: six kinds
- Dasyures: six kinds
- Koalas: five kinds
- Diprotodontoids: 16 kinds
- Marsupial lions: five kinds
- Wombats: five kinds
- Kangaroos: at least 35 kinds
- Possums: at least 31 kinds
- Bats: more than 40 kinds
- Platypus: one kind
- Marsupial moles: one kind
Dickson's Thylacine.
Copyright © A Musser.
Riversleigh Thylacine.
Photo: S Humphreys © Australian Museum.
Too numerous to mention
Countless tiny, delicate fossils belonging to lizards, fish and invertebrates have also been discovered but most have yet to be studied in detail.
Odd-bods
Many of Riversleigh's extinct animals are so strange that they have had to be put into distinctive groups of their own.
- Two species of weird pouched mammals have been called 'Thingodonta'. No one knows what they ate, how they lived or what they were related to.
- One weird mammal, named Yingabalanara, is so strange that it was nick-named 'Bizarrodonta'. Its relationships to other mammals are a complete mystery.
Record holder
Many discoveries at Riversleigh have set records.
- The world's tiniest possums
- Australia's oldest venomous snakes
- Among the world's best-preserved fossil insects
Last stands
Many other distinctive kinds of animals once common across Australia made their last stands at Riversleigh.
- Delicate, dog-size ilariids with teeth that resemble those of koalas
- Slender, vaguely wombat-like wynyardiids
Nimbadon (adult and juvenile).
Illustration: A Musser © Australian Museum.
Nimbadon skeleton
