The Bullock Creek Fossil site is one of three known

vertebrate Vertebrates () are animals with a vertebral column (backbone or spine), and a cranium, or skull. The vertebral column surrounds and protects the spinal cord, while the cranium protects the brain. The vertebrates make up the subphylum Vertebra ...

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

sites in the

Northern Territory The Northern Territory (abbreviated as NT; known formally as the Northern Territory of Australia and informally as the Territory) is an states and territories of Australia, Australian internal territory in the central and central-northern regi ...

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

, along with the Alcoota Fossil Beds and the Kangaroo Well site on Deep Well Station. It is located about south-southeast of Darwin, on Camfield Station in the locality of Victoria River. The Bullock Creek Fossil Site is part of the Camfield Fossil Beds which outcrop in a narrow belt about 50 km long. The Bullock Creek local fauna are approximately dated to the mid

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

(about 12 million years ago). The Camfield Fossil Beds which contain the Bullock Creek local fauna consist of light coloured calcareous

sandstone Sandstone is a Clastic rock#Sedimentary clastic rocks, clastic sedimentary rock composed mainly of grain size, sand-sized (0.0625 to 2 mm) silicate mineral, silicate grains, Cementation (geology), cemented together by another mineral. Sand ...

siltstone Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility. Although its permeabil ...

and

limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...

. Ferruginous mottling is found at the base and chalcedonic silification at the top. The presentation of fossils at the site ranges from poorly sorted fragmentary lags to associations with partial skeletons which includes complete crania (skulls) with intact delicate structures. The Bullock Creek Fossil Site is of natural significance in providing evidence for the evolution of the Northern Territory's fauna and climate. The Bullock Creek Fossil site is part of the Camfield Fossil Beds which are one of only a few Australian localities where rare fossil marsupials are well preserved. Among the fossils at the Bullock Creek site have been found complete marsupial crania with delicate structures intact. New significant taxa identified from the Bullock Creek mid Miocene include a new genus of crocodile, ''

Baru ''Baru'', sometimes referred to as the cleaver-headed crocodile, is an extinct genus of Australian mekosuchine crocodilian. Its fossils have been found from various Late Oligocene and Miocene localities from across the Northern Territory and Que ...

'' (''Baru darrowi''), a primitive true kangaroo, '' Nambaroo'', with high-crowned lophodont teeth; and a new species of giant horned tortoise, ''

Meiolania ''Meiolania'' is an extinct genus of meiolaniid stem-turtle native to Australasia throughout much of the Cenozoic. ''Meiolania'' was a large turtle, with the shell alone ranging from in length. Four species are currently recognized, although the ...

''. New marsupial lion,

thylacine The thylacine (; binomial name ''Thylacinus cynocephalus''), also commonly known as the Tasmanian tiger or Tasmanian wolf, was a carnivorous marsupial that was native to the Mainland Australia, Australian mainland and the islands of Tasmani ...

, and

dasyurid The Dasyuridae are a family of marsupials native to Australia and New Guinea, including 71 extant species divided into 17 genera. Many are small and mouse-like or shrew-like, giving some of them the name marsupial mice or marsupial shrews, but th ...

material has also been recovered. The extensive collection of ''

Neohelos ''Neohelos'' is an extinct diprotodontid marsupial, that lived from the early to middle-Miocene. There are four species assigned to this genus, ''Neohelos tirarensis'', the type species, ''N. stirtoni'', ''N. solus'' and ''N. davidridei''. ''N. d ...

'' (large browsing marsupial) remains from the Camfield beds has initiated a review of the mid Miocene zygomaturine diprotodontids. Together with the fossil assemblage in the Alcoota Fossil Beds to the north-east of Alice Springs, the Bullock Creek fossil fauna demonstrates systematic and community structural continuity from the mid to late Miocene in northern Australia. The Bullock Creek assemblage contains biological evidence of seasonality (trapping of small fish in drying backwaters), while lithostratigraphic evidence (interbedded evaporites) suggests longer periods of low precipitation and probably high ambient temperatures. The assemblage provides evidence that

aridification Aridification is the process of a region becoming increasingly arid, or dry. It refers to long term change, rather than seasonal variation. It is often measured as the reduction of average soil moisture content. It can be caused by reduced preci ...

was in progress in northern Australia during the Miocene. The fossil site was listed on the

Northern Territory Heritage Register The Northern Territory Heritage Register is a heritage register, being a statutory list of places in the Northern Territory of Australia that are protected by the Northern Territory statute, the '' Heritage Act 2011''. The register is maintained ...

on 3 August 1996 under the name "Bullock Creek Fossil Site."

References

Further reading