Riversleigh
Encyclopedia
Riversleigh, in North West Queensland
, is Australia
's most famous fossil
site. The 100 km² area has fossil remains of ancient mammals, birds and reptiles of Oligocene
and Miocene
age. The site was inscribed as a World Heritage site in 1994 and is an extension of the Boodjamulla National Park
.
The fossils at Riversleigh are rare because they are found in soft freshwater limestone
which hasn't been compressed. This means the animal remains retain their three dimensional structure.
was evolving from rich rainforest
to semi-arid grassland
community. Thirty-five fossil bat species have been identified at the site, which is the richest in the world. The skull and nearly complete dentition of a fifteen million-year-old monotreme
, Obdurodon dicksoni, provide a window into the evolution of this characteristically Australian group. Fossil ancestors of the recently extinct Thylacinus cynocephalus, the marsupial Tasmanian tiger, have also been identified among Riversleigh's fauna. In 1993, Nimbadon
skulls were unearthed in a previously unknown cave in the region. Researchers estimate that the prehistoric marsupial
first appeared about 15 million years ago and died out about 12 million years ago, perhaps from climate change induced losses in habitat. Other fossils have provided evidence of how the koala
has evolved in response to Australia's change from predominate rainforest vegetation to dryer eucalypt
forests.
s
Marsupial
s
Bird
s
Reptile
s
Queensland
Queensland is a state of Australia, occupying the north-eastern section of the mainland continent. It is bordered by the Northern Territory, South Australia and New South Wales to the west, south-west and south respectively. To the east, Queensland is bordered by the Coral Sea and Pacific Ocean...
, is Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
's most famous fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
site. The 100 km² area has fossil remains of ancient mammals, birds and reptiles of Oligocene
Oligocene
The Oligocene is a geologic epoch of the Paleogene Period and extends from about 34 million to 23 million years before the present . As with other older geologic periods, the rock beds that define the period are well identified but the exact dates of the start and end of the period are slightly...
and Miocene
Miocene
The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...
age. The site was inscribed as a World Heritage site in 1994 and is an extension of the Boodjamulla National Park
Boodjamulla National Park
Boodjamulla National Park, formerly known as Lawn Hill National Park, is a national park in the Gulf Country region of northwestern Queensland, Australia. The park is northwest of Mount Isa or northwest of Brisbane....
.
The fossils at Riversleigh are rare because they are found in soft freshwater limestone
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
which hasn't been compressed. This means the animal remains retain their three dimensional structure.
Fossils
Fossils at Riversleigh are found in limestone by lime-rich freshwater pools, and in caves, when the ecosystemEcosystem
An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving , physical components of the environment with which the organisms interact, such as air, soil, water and sunlight....
was evolving from rich rainforest
Rainforest
Rainforests are forests characterized by high rainfall, with definitions based on a minimum normal annual rainfall of 1750-2000 mm...
to semi-arid grassland
Grassland
Grasslands are areas where the vegetation is dominated by grasses and other herbaceous plants . However, sedge and rush families can also be found. Grasslands occur naturally on all continents except Antarctica...
community. Thirty-five fossil bat species have been identified at the site, which is the richest in the world. The skull and nearly complete dentition of a fifteen million-year-old monotreme
Monotreme
Monotremes are mammals that lay eggs instead of giving birth to live young like marsupials and placental mammals...
, Obdurodon dicksoni, provide a window into the evolution of this characteristically Australian group. Fossil ancestors of the recently extinct Thylacinus cynocephalus, the marsupial Tasmanian tiger, have also been identified among Riversleigh's fauna. In 1993, Nimbadon
Nimbadon
Nimbadon is an extinct genus of Diprotodontia that lived in the Miocene Epoch. Many fossils have been found in the Riversleigh World Heritage propertyin north-western Queensland.In 1990, skulls were unearthed in a previously unknown cave in the region...
skulls were unearthed in a previously unknown cave in the region. Researchers estimate that the prehistoric marsupial
Marsupial
Marsupials are an infraclass of mammals, characterized by giving birth to relatively undeveloped young. Close to 70% of the 334 extant species occur in Australia, New Guinea, and nearby islands, with the remaining 100 found in the Americas, primarily in South America, but with thirteen in Central...
first appeared about 15 million years ago and died out about 12 million years ago, perhaps from climate change induced losses in habitat. Other fossils have provided evidence of how the koala
Koala
The koala is an arboreal herbivorous marsupial native to Australia, and the only extant representative of the family Phascolarctidae....
has evolved in response to Australia's change from predominate rainforest vegetation to dryer eucalypt
Eucalypt
Eucalypts are woody plants belonging to three closely related genera:Eucalyptus, Corymbia and Angophora.In 1995 new evidence, largely genetic, indicated that some prominent Eucalyptus species were actually more closely related to Angophora than to the other eucalypts; they were split off into the...
forests.
Creatures
MammalMammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
s
- EkaltadetaEkaltadetaEkaltadeta is an extinct genus of giant marsupials related to modern rat-kangaroos.They are hypothesized to have been either predatory, or omnivorous with a fondness for meat, based on their chewing teeth. This conclusion is based mainly on the size and shape of a large buzz-saw-shaped cheek-tooth,...
, a carnivorous rat-kangarooPotoroidaeThe marsupial family Potoroidae includes the bettongs, potoroos, and two of the rat-kangaroos. All are rabbit-sized, brown, jumping marsupials and resemble a large rodent or a very small wallaby.- Characteristics :... - BurramysBurramysBurramys is a genus of the family Burramyidae, and is represented by one living and 3 extinct species. It is one of two genera of pygmy possum, the other being Cercartetus.-Taxonomy:*Genus Burramys**†Burramys wakefieldi...
, the Mountain Pygmy PossumMountain Pygmy PossumThe Mountain Pygmy Possum is a small, mouse-sized nocturnal marsupial of Australia found in dense alpine rock screes and boulder fields, mainly southern Victoria and around Mount Kosciuszko in Kosciuszko National Park in New South Wales at elevations from 1300 to 2230 m... - NimbacinusNimbacinusThe genus Nimbacinus contains two species both of which are extinct:* Dickson's Thylacine * ...
, a precursor of the Tasmanian wolfThylacineThe thylacine or ,also ;binomial name: Thylacinus cynocephalus, Greek for "dog-headed pouched one") was the largest known carnivorous marsupial of modern times. It is commonly known as the Tasmanian tiger or the Tasmanian wolf... - ObdurodonObdurodonObdurodon is an extinct monotreme genus containing three species. Obdurodon differed from modern platypuses in that it had molar teeth .-Obdurodon dicksoni:...
, a giant platypusPlatypusThe platypus is a semi-aquatic mammal endemic to eastern Australia, including Tasmania. Together with the four species of echidna, it is one of the five extant species of monotremes, the only mammals that lay eggs instead of giving birth to live young... - YaralaYaralaYarala is a genus of fossil mammals that resemble contemporary bandicoots. The superfamily Yaraloidea and family Yaralidae were created following the discovery of the type species Yarala burchfieldi in 1995, on the basis that it lacks synapomorphies that unite all other peramelemorphian taxa.A...
, a tube-nosed bandicootBandicootBandicoots are a group of about 20 species of small to medium-sized, terrestrial marsupial omnivores in the order Peramelemorphia.- Etymology :...
Marsupial
Marsupial
Marsupials are an infraclass of mammals, characterized by giving birth to relatively undeveloped young. Close to 70% of the 334 extant species occur in Australia, New Guinea, and nearby islands, with the remaining 100 found in the Americas, primarily in South America, but with thirteen in Central...
s
- Yalkaparidon, a bizarre marsupialMarsupialMarsupials are an infraclass of mammals, characterized by giving birth to relatively undeveloped young. Close to 70% of the 334 extant species occur in Australia, New Guinea, and nearby islands, with the remaining 100 found in the Americas, primarily in South America, but with thirteen in Central...
- WakaleoWakaleoWakaleo , was a genus of medium-sized thylacoleonids that lived in Australia in the early to late Miocene. It was approximately 2.5 ft long, or the size of a dog...
, a marsupial lionMarsupial lionThylacoleo is an extinct genus of carnivorous marsupials that lived in Australia from the late Pliocene to the late Pleistocene... - PriscileoPriscileoPriscileo was the basal-most genus of Thylacoleonidae. Fossils of this genus have been found in Oligocene and Miocene strata of South Australia and Queensland. It was about the size of a possum and was less powerful than the other marsupial lions...
, a marsupial lion - Nimiokoala, an ancient koalaKoalaThe koala is an arboreal herbivorous marsupial native to Australia, and the only extant representative of the family Phascolarctidae....
- NimbadonNimbadonNimbadon is an extinct genus of Diprotodontia that lived in the Miocene Epoch. Many fossils have been found in the Riversleigh World Heritage propertyin north-western Queensland.In 1990, skulls were unearthed in a previously unknown cave in the region...
, a sheep-like browser
Bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s
- PenganaPenganaThe Flexiraptor is an extinct species of bird of prey – the only one of its genus known to date – probably related to harriers. It probably resembled a cross between the Secretary Bird and Crested Caracara, and lived during the Early Miocene .Its remains were found in Riversleigh ,...
, a flexible-footed bird of preyBird of preyBirds of prey are birds that hunt for food primarily on the wing, using their keen senses, especially vision. They are defined as birds that primarily hunt vertebrates, including other birds. Their talons and beaks tend to be relatively large, powerful and adapted for tearing and/or piercing flesh.... - Menura tyawanoides, a prehistoric lyrebirdLyrebirdA Lyrebird is either of two species of ground-dwelling Australian birds, that form the genus, Menura, and the family Menuridae. They are most notable for their superb ability to mimic natural and artificial sounds from their environment. Lyrebirds have unique plumes of neutral coloured...
- The first fossil record of the OrthonychidaeOrthonychidaeThe Orthonychidae is a family of birds with a single genus, Orthonyx, which comprises three species of passerine birds endemic to Australia and New Guinea, the Logrunners and the Chowchilla. Some authorities consider the Australian family Cinclosomatidae to be part of the Orthonychidae...
(logrunner) family
Reptile
Reptile
Reptiles are members of a class of air-breathing, ectothermic vertebrates which are characterized by laying shelled eggs , and having skin covered in scales and/or scutes. They are tetrapods, either having four limbs or being descended from four-limbed ancestors...
s
- TrilophosuchusTrilophosuchusTrilophosuchus is an extinct genus of the crocodilian subfamily Mekosuchinae. Unlike living crocodilians, it is hypothesized to have been terrestrial. Trilophosuchus was approximately in length. It had a short skull with three ridges on top and large eyes. Fossils have been found at Riversleigh...
, a tree-dwelling crocodileCrocodileA crocodile is any species belonging to the family Crocodylidae . The term can also be used more loosely to include all extant members of the order Crocodilia: i.e... - BaruBaruBaru was an extinct genus of Australian mekosuchine crocodilian. It was semi-aquatic, around 4 m in length. Being semi-aquatic its habitat was around fresh pools of water in wet forests, ambushing their prey, much like modern species...
, the cleaver-headed crocodile - Yurlunggur, and WonambiWonambiWonambi is a genus that consisted of two species of very large snakes. These species were not pythons, like Australia's other large constrictors of the genus Morelia, and are now a member of an extinct family Madtsoiidae...
, extinct snakes (MadtsoiidaeMadtsoiidaeMadtsoiidae are an extinct group of mostly Gondwanan snakes with a fossil record extending from early Cenomanian to late Pleistocene strata located in South America, Africa, India, Australia and Southern Europe...
)