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Australian Fossil Mammal Sites (Riversleigh), Riversleigh via Gregory Downs, QLD, Australia

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List World Heritage List
Class Natural
Legal Status Declared property (17/12/1994)
Place ID 105088
Place File No 4/07/287/0002
Statement of Significance
Over 2000 kilometres separate the two sites which form the World Heritage property. Riversleigh (10 000 hectares), located in north western Queensland, is confined to the watershed of the Gregory River. The site at Naracoorte, South Australia, covers 300 hectares and is located in flat country, punctuated by a series of stranded coastal dune ridges that run parallel to the present coastline.
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.
In stark contrast to the semi-arid conditions at Riversleigh stand the cool caves at Naracoorte. Here are fossils that document a distinctive fauna, with the ancestors of modern species alongside the doomed giants of a world that was about to be devastated by climatic changes.
The fossils in the Naracoorte Caves illustrate faunal change spanning several ice ages, highlighting the impacts of both climatic change and humankind on Australia's mammals from at least 350 000 years before the present.
Further research at the Naracoorte Caves sites is expected to document a series of snapshots of Pleistocene life in south east Australia, including details of climate and vegetation associated with the fauna. Recent geological research suggests that deposits of Pliocene and even Miocene age could be found at the site, thus providing closer links with the site at Riversleigh.
Specimens representing 99 vertebrate species have been discovered, ranging in size from very small frogs to buffalo-sized marsupials. These include exceptionally preserved examples of the Australian Ice Age megafauna, as well as a host of modern species such as the Tasmanian devil, thylacine and others. The Naracoorte fossils span the probable time of the arrival of humans in Australia, and this is valuable in analysing the complex relationships between humans and their environment.
Both sites provide evidence separately of key stages in the evolution of the fauna of the world's most isolated continent. The history of mammal lineages in modern Australia can be traced through these fossil deposits and, as a consequence, there is a better understanding of the conservation status of living mammals and their communities.
The sites, each highly significant in its own right, are presented as a serial World Heritage nomination. Together they represent the key stages in the development of Australia's mammal fauna. While there are other important Australian fossil mammal sites, Riversleigh and Naracoorte are outstanding for the extreme diversity and the quality of preservation of their fossils. They also provide links through time that unify the biotas of the past with those of today in the Wet Tropics of Queensland, the Gondwana Rainforests of Australia and Kakadu National Park World Heritage properties.
 
Official Values
Criterion (IX) Outstanding examples of on-going evolution
Riversleigh is an outstanding example representing significant ongoing ecological and biological processes in the evolution and development of Australia's mammal fauna. It is the richest Australian, and one of the world's richest, Oligo-Miocene mammal records, linking that period (15-25 million years) to the predominantly modern assemblages of the Pliocene and Pleistocene.
The World Heritage values of Riversleigh include:
  • the fossil mammal record, which shows continuity and the effects of evolutionary and environmental change over at least the last 20 million years;
  • the quality and quantity of the fossil deposits, which has provided increased understanding of the past, present and possible future evolutionary path of many mammal species;
  • the Oligo-Miocene mammal record, the richest for the continent and one of the richest in the world, which includes fossil assemblages and sequences that:
  • provide evidence of temporal sequence of Oligo-Miocene rainforest mammals in Australia;
  • link the Oligo-Miocene assemblages of central Australia and the dominantly modern assemblages of the Pliocene and Pleistocene of eastern Australia;
  • provide evidence for the evolution of Australia's modern dry country mammal assemblages from ancestors within Australia's Oligo-Miocene rainforests;
  • preserve an important sequence of mammal species from Tertiary rainforest biotas;
  • provide a connection to other faunas within Australia;
  • show evolutionary and ecological continuity to other World Heritage properties within Australia;
  • allow examination of community structure as well as the more conventional morphological and taxonomic study of particular individuals;
  • preserve examples of unique Australian prehistoric animals over the last 25 million years, including marsupial lions, carnivorous kangaroos, diprotodontids, huge pythons, early ancestors of the Tasmanian tiger, platypuses, crocodiles and bats;
  • provide an important collection of bat fossils in terms of the quantity and preservation of specimens;
  • include the oldest known specimens of many of Australia's mammal families (e.g. feather tailed possums, marsupial moles, wombats, gliding possums) which are amongst the best known in the world due to their quantity and degree of preservation; and
  • other fossil vertebrates and invertebrates, including some of which are Australia's oldest samples (e.g. millipedes, slaters and other arthropods).
 
Criterion (VIII) Outstanding examples of stages of earth's history
Riversleigh is an outstanding example representing major stages of earth's history, including the record of life, particularly the middle to late Tertiary evolution of the mammals in Australia, and significant on-going geological processes. The World Heritage values of Riversleigh include:
 
Fossil deposits which:
  • contain an exceptional abundance and diversity of species and individual specimens;
  • include important and unique examples of middle to late Tertiary mammal assemblages;
  • demonstrate a rich Oligo-Miocene mammal record, including representation of rainforest species;
  • represent unusually wide temporal periods within the fossil record, including timeframes when Australia has been the most isolated continent on earth;
  • have a high quality of preservation of specimens; and
  • include evidence of links between the Australian mammal fauna with faunas outside Australia;
  • diverse Tertiary sediments which contain the fossil assemblages, particularly the Oligo-Miocene cave, fissure and alluvial tufa deposits which are geological antecedents to similar carbonate deposits that still form in the region today.
 
Description
The Tertiary fossil fields of Riversleigh are apparently confined to the watershed of the spring fed Gregory River within the Karumba Basin in the Gulf of Carpentaria. The Cainozoic deposits of Riversleigh occur as inliers within eroded areas of the extensive, flat-lying, Cambrian Thorntonia limestone. This in turn surrounds less common remnants of Proterozoic sediments. The Cainozoic sediments can be categorised into four groups: Oligo-Miocene alluvial and lacustrine deposits; Oligo-Miocene karst and fissure fills; Pliocene cave sediments; and Quaternary fluvial and cave sediments.
 
Riversleigh's faunal assemblages have profoundly altered understanding about Australia's mid-Cainozoic vertebrate diversity. A 15 million-year-old complete skull and nearly complete dentition of the monotreme Obdurodon dicksoni (Archer et al. 1992, 1993) has already provided a great deal of new information about this highly distinctive group of mammals.
The recently extinct marsupial thylacine Thylacinus cynocephalus, also known as the Tasmanian Tiger, was the largest living mammalian carnivore in Australia. Before Riversleigh's fossil record began to unfold, there was only one Tertiary species known, but different thylacines have been identified from Riversleigh's Oligo-Miocene faunas (Muirhead & Archer 1990; Muirhead 1993). This record has been used (Archer l991a, Archer et al., 1992) to demonstrate the potential conservation value of understanding the prehistory of a group, although in this case understanding was obtained too late to be of value in avoiding the extinction of the Thylacine in the 1930s. Other ancestral marsupial forms found at Riversleigh include moles, bandicoot, marsupial 'lions', koala, wombat, kangaroo and possums. Placental mammals are represented by more than 35 bat species, and the Riversleigh fossil bat record is considered one of the richest in the world.
The landscape at Riversleigh, particularly near the rivers, has a large number of visible archaeological traces of Aboriginal occupation and sites of cultural significance.
 
History Not Available
Condition and Integrity Not Available
Location
About 10 000ha, 70km south west of Gregory Downs, comprising that part of Boodjamulla (Lawn Hill) National Park inscribed in the World Heritage List in 1994.
Bibliography
Archer, M. et al (1986) Uncovering Australia's Dreamtime  Surrey Beatty, Chipping North NSW.
Archer, M. et al (1991) Riversleigh: the Story of Australia's Inland Rainforests Reed Books, Sydney.
Cochrane, R.M. and Joyce, E.B. (1986) Geological Features of National and International Significance in Australia  Australian Heritage Commission, Canberra.
Gould, S.J. (1993) The Book of Life  Ebury Hutchinson, London.
Rich, P.V. and van Tets, G.F. (1985) Kadimakara: Extinct Vertebrates of Australia  Pioneer, Lilydale.
 

Report Produced  Thu Jul 31 12:14:49 2014