Australian Fossil Mammal Sites

Australian Fossil Mammal Sites, Australia

Published: April 7, 2009, 5:36 pm

Topics:

Biodiversity (main) Geography (main) Evolutionary Biology (main)

Geographical Location

The Australian Fossil Mammal Sites are two World Heritage Sites that are widely separated across Australia, in the states of South Australia and Queensland.

Riversleigh (18°59'-19°08'S, 138°34'-138°43'E) comprises the southern section of Lawn Hill National Park in north-west Queensland.

Naracoorte (37°S, 140°48'E) lies in the south-east of South Australia, 11 kilometers (km) south-south-east of Naracoorte township and approximately 320 km south-east of Adelaide.

Date and History of Establishment

Riversleigh, Australia. (Source: Australian Government: Department of the Environment and Water Resources)

Riversleigh was gazetted as part of the Lawn Hill National Park under the Queensland National Park and Wildlife Act 1975 in 1984.

Naracoorte Caves were gazetted in 1917. The Naracoorte Caves Conservation Park was proclaimed under the South Australia National Parks and Wildlife Act 1972.

The Australian Fossil Mammal Sites were inscribed on the World Heritage List in 1994.

Area

10,300 hectares (ha). Comprises Riversleigh (10,000 ha) and Naracoorte (300 ha).

Land Tenure

Riversleigh is owned by the State of Queensland; and Naracoorte is owned by the State of South Australia.

Altitude

No information.

Physical Features

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 categorized into four groups: Oligo-Miocene alluvial and lacustrine deposits; Oligo-Miocene karst and fissure fills; Pliocene cave sediments; and Quaternary fluvial and cave sediments.

Naracoorte is located in flat country, punctuated by a series of stranded coastal dune ridges that run parallel to the present coastline. The region is one of covered karst. The caves of the Naracoorte Caves Conservation Park are formed in a ridge of Oligo-Miocene Gambier limestone capped by the Naracoorte East Dune. In the Late Pleistocene the caves were open to the surface allowing sediment and bones to accumulate in their entrances and dolines, the most significant of these accumulations being those of Victoria Fossil Cave. The south-east region's natural history, including its geography, hydrology, ecosystems and flora and fauna has been described in detail in Tyler et al. (1983).

Climate

Naracoorte has a cool, moist climate with long, mild, relatively dry summers and maximum rainfall occurring in winter. Riversleigh experiences dry winters and cool summers with monsoonal rainfall.

Vegetation

Not applicable.

Fauna

The Thylacinus cynocephalus, or the Tasmanian Tiger, was the largest living mammalian carnivore in Australia until it recently became extinct. (Source: University of Tasmania)

The two sites were nominated on the basis of their importance as fossil sites, representative of the development of Australia's mammal fauna; the following information therefore relates to the fossil fauna only.

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 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. This record has been used 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 Pleistocene fossil vertebrate deposits of Victoria Fossil Cave at Naracoorte are considered to be, in terms of both volume and diversity, Australia's largest and best preserved, and one of the richest deposits of in the world. From the 3-4 meters (m) deep Fossil Bed, tens of thousands of specimens representing at least 93 vertebrate species have been recovered, ranging in size from very small frogs to buffalo-sized marsupials. These include superbly preserved examples of the Australian Ice Age megafauna as well as a host of essentially modern species such as the Tasmanian Devil and Thylacine, wallabies, possums, bettongs, mice, bats, snakes, parrots, turtles, lizards and frogs. The fossil material includes complete postcranial remains (many of which are partially articulated) and skulls so well preserved that even the most delicate bones are still intact. The fossil remains are believed to have steadily accumulated over thousands of years until sediment pouring into the Cave completely blocked the entrances to the chambers.

Cultural Heritage

The landscape at Riversleigh, particularly near the rivers, has a large number of visible archaeological traces of Aboriginal occupation and sites of cultural significance.

Local Human Population

The nominated site at Riversleigh lies on the south-western boundary of the Waanyi Aboriginal clan territory. No Aboriginal people currently reside within the nominated site, although appropriate involvement will be sought in the management of identified cultural sites. Information on the other nominated sites is not available.

Visitors and Visitor Facilities

An estimated 800,000 people (of whom about 10% were overseas visitors) have participated in guided interpretive tours of Victoria Fossil Cave at Naracoorte since 1969. An information shelter funded by the Australian Geographic Society provides basic interpretation of the fossils at Riversleigh.

Scientific Research and Facilities

Broad research projects currently focused on the mammals of Riversleigh and Victoria Fossil Cave cover diversity in Australia's prehistoric mammals; changes in the structure of Australia's Cainozoic terrestrial mammal communities; biocorrelative framework for Australia's Cainozoic mammal-bearing sediments; palaeobiogeographic history of Australia's mammals; correlation of events in the Cainozoic history of Australian mammals with those hypothesized on the basis of palaeobotany and marine invertebrates; and understanding the changes through time in communities to determine appropriate conservation strategies.

Updated lists of publications, technical and popular, relating to both Riversleigh are published four times a year in Riversleigh Notes, the newsletter of the Riversleigh Society Inc.

Conservation Value

The sites, each highly significant in their own right, are presented as a serial World Heritage nomination because, taken together, their significance is united and transcended by their being representatives of key stages in the development of Australia's mammal fauna. While there are other mammal fossil sites known from Australia, these sites represent extreme diversity and/or quality of preserved materials. They also represent links through time that unify the biotas of the past with those of today such as those in the Wet Tropics of Queensland, the East Coast Rainforests of Australia and Kakadu National Park World Heritage properties.

In addition, they provide a basis for documenting evolutionary change in the lineages and communities that have led to the modern biota. This may be valuable in the development of conservation strategies.

Conservation Management

The Riversleigh nominated site is contained within the Riversleigh Management Unit of the Lawn Hill National Park. Due to the rugged limestone terrain, European activity is restricted to grazing, palaeontological research and education. Until recently, the Riversleigh was a grazing property. In 1992 the nominated site was acquired for National Park purposes with arrangements for cattle grazing to continue under permit for a period of seven years. Research undertaken by palaeontologists involves the removal of fossil-bearing limestone from the nominated site under permit. Explosives may be used to extract limestone, although its impact is restricted to very small areas. Education is a small but significant use, although impact from visitors can be controlled in the National Park because removal of any material from the park without a permit is prohibited. Recreation on the proposed Gregory Resources Reserve which abuts the nominated site attracts a small but increasing number of campers and day visitors to the area although impact from recreation on the nominated site is not considered to be significant. The impact of cattle grazing is very minor, as stocking rates have been low. Minor infestations of weed species occur along the Gregory River but these areas do not affect the nominated site. The most significant impact on the natural condition of the nominated site is the collection of fossil-bearing limestone by palaeontological researchers. However, the impact is minor and localized. A draft management plan has been compiled.

Visitor access at Naracoorte is controlled to protect the scientific, conservation and aesthetic values of the caves. A management plan for the Naracoorte Caves has been prepared in pursuance of Section 38 of the National Parks and Wildlife Act 1972-81.

Management Constraints

No information.

Staff

No information.

Budget

The Commonwealth Government has provided funds to assist in the management of these properties.

Other Information - Paleohabitat

Fossil deposits discovered in Riversleigh, Australia. (Source: Environmental Protection Agency)

The two sites appear to represent quite distinct paleohabitats. Riversleigh's late Oligocene to early and middle Miocene (possibly 25-12 my) assemblages have been interpreted by Archer et al. (1989) and Archer et al., (1991) to represent rainforest communities. These are biotically more diverse (some with 64 mammal species) than any other Tertiary or modern Australian mammal assemblages. Arboreal forms (possums and koalas) are proportionately abundant, with up to twelve species of obligate folivores in some deposits.

The loss of family- and generic-level diversity in mammals between the early and middle Miocene suggest a first response to a change in climatic (Climate change) conditions or botanical biodiversity in the region. Gradual declines in rainforest plant species characterize the middle to late Miocene of other areas of Australia, although arid conditions are unknown from the continent prior to the Plio-Pleistocene.

Riversleigh's Pliocene habitats may not have included rainforest. The abundance of granivorous rodents and the occurrence of marsupial genera (e.g., species of Planigale and Sminthhopsis) that dominate dry habitats of modern Australia suggest that if rainforest was present, it was confined to refugia within the region. Palaeohabitats for the Pleistocene and early Holocene of the Riversleigh region are as yet unclear.

One of the opportunities offered by the fossil record is to unite rainforest mammal lineages and communities beginning with the early to middle Miocene Australian lowland rainforest assemblages at Riversleigh, through the southern lowland rainforests of Pliocene south-eastern Australia (Hamilton Local Fauna) to the rainforests of contemporary northeastern Queensland and New Guinea. This continuum highlights the significance of modern rainforest refugial mammals now confined to the [[Wet Tropics of Queensland] World Heritage property].

Similarly, the mammal lineages in Riversleigh's rainforest and non-rainforest habitats anticipate open-forest lineages, such as those that occur in Kakadu National Park. These lineages adapted to loss of the lowland rainforests sometime between the late Miocene and early Pliocene. The potential value of these four-dimensional connections is considered by Archer et al. (1991, 1992).

IUCN Management Category

• Not applicable
• Natural World Heritage Site - Criteria i, ii

Further Reading

The material presented in this data sheet has been drawn from:

• DEST (1993). Nomination of Australian Fossil sites (a serial nomination of sites at Murgon, Riversleigh and Naracoorte). Department of the Environment, Sport and Territories. 56pp.

Other (Unseen) citations in the text:

• Archer, M., 1991a. Life's scroll of prophecy: conservation & the fossil record. Aust. Nat. Hist. 23: 654-55.
• Archer, M., Hand, S.J., Godthelp, H., 1991. "Riversleigh". Reed Books: Sydney. ISBN: 0730103145.
• Archer, M., Hand, S.J., Godthelp, H., 1992. Back to the future: the contribution of palaeontology to the conservation of Australian forest faunas. Pp. 67-80 in "Conservation of Australia's forest fauna" ed D. Lunney. Royal Zoological Society for New South Wales: Sydney. ISBN: 0959995153.
• Archer, M., Jenkins Jr, F.A., Hand, S.J., Murray, P., Godthelp, H., 1992. Descriptions of the skull and non-vestigial dentition of a Miocene platypus (Obdurodon dicksoni n. sp.) from Riversleigh, Australia, and the problem of monotreme origins. Pp. 15-27 in 'Possums and echidnas' ed M.L. Augee. Royal Zoological Society of New South Wales: Sydney.
• Archer, M., Murray, P., Godthelp, H., Hand, S.J., 1993. Reconsideration of Monotreme Relationships Based on the Skull and Dentition of the Miocene Obdurodon dickson n. sp. (Ornithorhynchidae) from Riversleigh, Queensland, Australia. Pp. 75-94. In "Mammalian phylogeny Vol. 1" ed. F. Szalay, M. Novacek, M. McKenna. Springer/Verlag: Germany.
• Martin, H.A., 1993. Australian Tertiary phytogeography. In 'Origins of the Australian vegetation' ed. R. Hill. Cambridge University Press: London.
• Molnar, R., 1982. A catalogue of fossil amphibians and reptiles in Queensland. Mem. Qd Mus. 20: 613-33.
• Muirhead, J., 1993. Thylacinus macknessi, a specialised thylacinid (Marsupialia: Thylacinidae) from Miocene deposits of Riversleigh, north-western Queensland. Aust. Mammal. 15: 67-76.
• Rich, T.H., Archer, M., Hand, S.J., Godthelp, H., Muirhead, J., Pledge, N.S., Flannery, T.F., Woodburne, M.O., Case, J.A., Tedford, R.H., Turnball, W.D., Lundelius, E.L., Rich, L., Whitelaw, M.J., Rich, P.V., 1991. In "Vertebrate palaeontology of Australasia" ed P.V. Rich, J.M. Monagan, R.F. Baird, T.H. Rich. Pioneer Design Studio: Melbourne. ISBN: 0909674361.
• Muirhead, J., Archer, M., 1990. Nimbacinus dicksoni, a plesiomorphic thylacine (Marsupialia: Thylacinidae) from Tertiary deposits of Queensland and the Norhtern Territory. Memoirs of the Queensland Museum 28: 203-21.
• Oates, L.F. (1975). The 1973 Supplement to a Revised Linguistic Survey of Australia. Armidale Christian Boo Centre, Armidale. ISBN: 0959839003.
• Oates, W.J. and Oates, L.F. (1970). A Revised Linguistic Survey of Australia. Australian Aboriginal Studies No. 33, Linguistic Studies No. 12 Australian Institute of Aboriginal Studies, Canberra 1970. ISBN: 0855750103.
• Queensland Department of Environment and Heritage. 1994. Riversleigh Management Unit: Lawn Hill National Park. Draft Plan of Management. 40pp.
• Sigé, B., 1991. Rhinolophoidea et Vespertilionoidea (Chiroptera) du Chambi (Eocène inférieur de Tunisie). Aspects biostratigraphique, biogéographique and paleoécologique de l'origine des chiroptères modernes. Neues jahrb. Geol. Palaönt. Abhandl. 182: 355-76.
• South Australia National Parks and Wildlife Service. 1992. Naracoorte Caves Conservation Park Management Plan. Department of Environment and Planning. 28pp.
• Szalay, F.S., 1982. A new appraisal of marsupial phylogeny and classification. Pp. 621-40 in 'Carnivorous marsupials', ed. by M. Archer. Surrey Beatty and Sons and the Royal Zoological Society of New South Wales: Sydney.
• Tindale, N.B. (1974). Aboriginal Tribes of Australia: their terrain, environmental controls, distribution, limits and proper names. Australian National University Press, Canberra. ISBN: 0520020057.
• Tyler, M.J., Twidale, C.R., Ling, J.K. and Holmes, J.W. (eds), 1983. Natural History of the south-east. Roy. Soc. S. Aust.: Adelaide.
• Wells, R.T., 1975. Reconstructing the past - excavations in Victoria Fossil Cave. Aust. Nat. Hist. 18(6): 208-11.
• Wells, R.T., Moriarty, K. and Williams, D.L.G., 1984. The fossil vertebrate deposits of Victoria Fossil Cave: an introduction to the geology and fauna. Aust. Zool. 21(4): 305-33.

Disclaimer: This article is taken wholly from, or contains information that was originally published by, the United Nations Environment Programme-World Conservation Monitoring Centre (UNEP-WCMC). Topic editors and authors for the Encyclopedia of Earth may have edited its content or added new information. The use of information from the United Nations Environment Programme-World Conservation Monitoring Centre (UNEP-WCMC) should not be construed as support for or endorsement by that organization for any new information added by EoE personnel, or for any editing of the original content.

Citation

M, U. (2009). Australian Fossil Mammal Sites, Australia. Retrieved from http://editors.eol.org/eoearth/wiki/Australian_Fossil_Mammal_Sites