The Winton Formation is a

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

geological formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics (lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock expo ...

in central-western

Queensland ) , nickname = Sunshine State , image_map = Queensland in Australia.svg , map_caption = Location of Queensland in Australia , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , established_ ...

, Australia. It is late

Albian The Albian is both an age of the geologic timescale and a stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early/Lower Cretaceous Epoch/ Series. Its approximate time range is 113.0 ± 1.0 Ma to 100.5 ± ...

to early Turonian in age. The formation blankets large areas of central-western Queensland. It consists of

sedimentary rock Sedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral or organic particles at Earth's surface, followed by cementation. Sedimentation is the collective name for processes that cause these particle ...

s such as

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates ...

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.Blatt ''et al.'' 1980, ...

and claystone. The

sediment Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sa ...

s that make up these rocks represent the remnants of the river plains that filled the basin left by the Eromanga Sea - an inland sea that covered large parts of Queensland and central Australia at least four times during the Early Cretaceous. Great meandering rivers, forest pools and swamps, creeks, lakes and coastal estuaries all left behind different types of sediment. In some areas, the Winton Formation is over 400 metres thick. To bring with them such a huge amount of sediment, the rivers that flowed across these plains must have been comparable in size to the present-day

Amazon Amazon most often refers to: * Amazons, a tribe of female warriors in Greek mythology * Amazon rainforest, a rainforest covering most of the Amazon basin * Amazon River, in South America * Amazon (company), an American multinational technolog ...

Mississippi Mississippi () is a state in the Southeastern region of the United States, bordered to the north by Tennessee; to the east by Alabama; to the south by the Gulf of Mexico; to the southwest by Louisiana; and to the northwest by Arkansas. Mis ...

rivers. As more and more sediment was brought in, the margins of the inland sea slowly contracted. By around 95 million years ago, the deposition was complete and the inland sea would never be seen again. By virtue of its age and the environmental conditions under which the rocks it consists of were deposited, the Winton Formation represents one of the richest sources of dinosaur fossils anywhere in Australia.

Fauna

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 preserved ...

footprint-( ichnite), ''Wintonopus'', found with two other dinosaur genera footprints at the Lark Quarry in Australia, c.f. ''Tyrannosauropus'' and ''Skartopus'', have been found in the Winton Formation.

Dipnoi

Actinopterygii

Crocodyliformes

Dinosaurs

Pterosaurs

Flora

References

{{reflist Geologic formations of Australia Cretaceous System of Australia Early Cretaceous Australia Albian Stage Cenomanian Stage Turonian Stage Sandstone formations Siltstone formations Coal in Australia Shale formations Fluvial deposits Ichnofossiliferous formations Fossiliferous stratigraphic units of Oceania Paleontology in Queensland Formations Formations