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| Ducabrook Formation | |
|---|---|
| Stratigraphic range: Mississippian (Viséan), | |
| Type | Geological formation |
| Unit of | Drummond Basin[1] |
| Underlies | Joe Joe Formation, Colinlea Sandstone |
| Overlies | Star of Hope Formation |
| Thickness | Up to 2,100 m (6,900 ft) |
| Lithology | |
| Primary | Sandstone, mudstone[1] |
| Other | Tuff, conglomerate facies, limestone |
| Location | |
| Location | Springsure, Queensland |
| Coordinates | 24°06′58″S 148°05′19″E / 24.1161°S 148.0886°E |
| Region | Queensland |
| Country | Australia |
  Ducabrook Formation (Australia)  Ducabrook Formation (Queensland) | |
The Ducabrook Formation is a Carboniferous period geological formation located near Springsure in Queensland, Australia.[1] It dates specifically to the Viséan stage of the Mississippian subperiod, between approximately 346 to 330 million years ago.[2]
Geology
[edit]The Ducabrook Formation is up to 2,100 meters thick, and is the youngest unit of the Drummond Basin, and outcrops occur only in the southern part of the basin. The geology consists of a sequence of interbedded sandstone and mudstone, primarily khaki-brown and olive-green in colour, with occasional beds made of tuff, conglomerate, and limestone.[1] These sediments likely accumulated in shallow fluvialite and lacustrine environments. The formation overlies the Star of Hope Formation conformably, and is uncomforably overlain by either the Joe Joe Formation or Colinlea Sandstone, depending on the specific area.[1] The Middle Paddock Locality (QM L1117) itself consists of grey-green fragile to hard sandstone coating bones with microscopic orange-brown roundish pebbles.[3]
History of the Middle Paddock locality
[edit]The Middle Paddock (QM L1117)[4][5], the most productive site of the Ducabrook Formation, contains an eroded drainage area at the head of a small stream system. The locality was discovered in 1995 by local landowners who sent gyracanth and tetrapod spine fragments to the Queensland Museum. Scientists later made a visit to the site when surfaced bones, some hailing from tetrapods, were collected over a four-hour timeframe.[5]
In 1996, a five-day trip established the area over which more bones were weathering and worked the immediate vicinity for further exposures. Strata rich in palaeoniscoids were discovered, but nothing comparable to the larger fish or tetrapod fossils found at the main site. Small-scale excavation of the supposed main locality was carried out to record the state of preservation of in situ bone. Multiple well-preserved tetrapod postcranial elements were recovered from an area known as Middle Rise.[5]
In 1997, another field trip at the site was gridded with iron stakes at 10 meter intervals, to be left in place permanently. The grid, measuring about 60 meters north to south and 70 meters east to west, covers the entirety of the fossil-bearing surface. All bones obtained has been designated as to grid square for future taphonomic study and entered onto an ACCESS database. At Middle Rise, a more extensive excavation began, concurrent with minor excavations elsewhere in search of more productive areas, which continued through 1998.[5]
Between 1999 and 2001, the Middle Rise area was subsequently subdivided into 1 meter quares from which all material found was recorded with details. These twenty-two weeks of fieldwork have produced some 60 tetrapod elements representing at least four individuals.[5]
Fossil content
[edit]Gnathostomata
[edit]| Genus | Species | Clade | Images |
|---|---|---|---|
| Ctenodus | C. boudariensis[6] | Ceratodontiformes, | |
| Gyracanthides | G. hawkinsi[7] | Climatiiformes, |  |
| Ossinodus | O. pueri[5] | Stegocephalia, |  |
| Reginaselache | R. morrisi[4] | Xenacanthiformes, | |
| Strepsodus | S. sp.[2][8] | Rhizodontiformes, |
References
[edit]- 1 2 3 4 5 Olgers, F. (1972). Geology of the Drummond Basin, Queensland. Bulletin 132. Bureau of Mineral Resources, Geology and Geophysics.
- 1 2 Johanson Z.; Turner S.; Warren A. (2000). First East Gondwanan record of Strepsodus (Sarcopterygii, Rhizodontida) from the Lower Carboniferous Ducabrook Formation, central Queensland, Australia. Geodiversitas, 22(2), 161–169.
- ↑ Turner, S.; Kemp, A.; Warren, A. A. (1999). First Early Carboniferous lungfish (Dipnoi, Ctenodontidae) from central Queensland. Alcheringa: An Australasian Journal of Palaeontology, 23(3), 177–183.
- 1 2 Turner, S. and Burrow, C. J. (2011). A Lower Carboniferous xenacanthiform shark from Australia. Journal of Vertebrate Paleontology, 31(2), 241–257.
- 1 2 3 4 5 6 Warren, A.; Turner, S. (2004). The first stem tetrapod from the Lower Carboniferous of Gondwana. Palaeontology, 47(1), 151–184.
- ↑ Kemp, A. (2019). Ctenodus boudariensis nov. sp., a ctenodont lungfish from the mid-Viséan Ducabrook Formation of Queensland, Australia. Alcheringa: An Australasian Journal of Palaeontology, 43(3), 423–429.
- ↑ Turner, S.; Burrow, C. J.; Warren, A. (2005). Gyracanthides hawkinsi sp. nov. (Acanthodii, Gyracanthidae) from the Lower Carboniferous of Queensland, Australia, with a Review of Gyracanthid Taxa. Palaeontology, 48 (5), 963–1006.
- ↑ Parker, K.; Warren, A. A.; Johanson, Z. (2005). Strepsodus (Rhizodontida, Sarcopterygii) pectoral elements from the Lower Carboniferous Ducabrook Formation, Queensland, Australia. Journal of Vertebrate Paleontology, 25(1), 46–62.