Oreochima | |
---|---|
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Actinopterygii |
Family: | † Archaeomaenidae |
Genus: | † Oreochima Schaeffer & Elliot, 1972 |
Species: | †O. ellioti |
Binomial name | |
†Oreochima ellioti Schaeffer & Elliot, 1972 | |
Oreochima is an archaeomaenid ray-finned fish from Lower Jurassic-aged freshwater strata of Queen Alexandra Range, Antarctica. Fossils come from the Lower Jurassic Mawson Formation (Toarcian) of Storm Peak, Antarctica, where a freshwater lake system, called "Lake Carapace", once existed. [2] O. ellioti is also notable for being one of few archaeomaenid genera found outside of Australia, as well for be one of the oldest members of the family. [2] [3]
Two nearly complete specimens of Oreochima ellioti (specimens AMNH 9910 and AMNH 9916) have an average total length of about 60 mm, with incomplete specimens represent individuals of similar size. [2] The frontals taper anteriorly and were slightly notched where they were in contact with the nasals. The opercular bone was about twice as high as the subopercular. [2]
The cladogram below is simplified after a phylogenetic analysis by Bean (2021). Archaeomaenidae was recovered as one of the most basal stem-teleost clades, lying crownward of the families Pachycormidae and Aspidorhynchidae, but stemward of the family Pholidophoridae: [3]
The Mawson Formation represents the fossiliferous interbeds of the Kirkpatrick Basalt, part of the Ferrar Group volcanic events, with age constraint in between 180+/-3.5 Ma-176.6+/-1.8 Ma, well correlated with the evolution of the Ferrar Large Igneous Province during the initial breakup of Gondwana. [3] This layers record sedimentary and biotic processes in relatively shallow lakes and ponds, and in surrounding wetlands to upland areas, with the biota of the lakes having access to magmatic sources. The so called "Lake Carapace", the main water body recovered locally, was, like the "Chacritas Paleolake" of the sister Cañadón Asfalto Formation in Patagonia, developed following the local rift in a similar way to the modern Lake Magadi in the Kenyan Rift Valley, as proven by the discovery of Chert like the one found in this African lake, that suggests both, Carapace and Chacritas were likely alkaline lakes that had inflows of hydrothermal fluids. [4] Hydrothermal activity help the development of microbes (Archaea) and helping the fauna on cooler events. Alongside Oreochima lived the spinicaudatan Carapacestheria disgregaris, notostracan branchiopods, ostracoda, up to 50 specimens of insect nymphs and wings (mayflies, the dragonfly Caraphlebia antartica, and a Coleopteran). [5] [6] and plant leaves ( Zamites ). [7] [8]
Cryolophosaurus is a genus of large theropod dinosaur known from only a single species Cryolophosaurus ellioti, from the early Jurassic of Antarctica. It was one of the largest theropods of the Early Jurassic, with the subadult being estimated to have reached 6–7 metres (20–23 ft) long and weighed 350–465 kilograms (772–1,025 lb).
Stupendemys is an extinct genus of freshwater side-necked turtle, belonging to the family Podocnemididae. It is the largest freshwater turtle known to have existed, with a carapace over 2 meters long. Its fossils have been found in northern South America, in rocks dating from the Middle Miocene to the very start of the Pliocene, about 13 to 5 million years ago. Male specimens are known to have possessed bony horns growing from the front edges of the shell and the discovery of the fossil of a young adult shows that the carapace of these turtles flattens with age. A fossil skull described in 2021 indicates that Stupendemys was a generalist feeder.
The Hanson Formation is a geologic formation on Mount Kirkpatrick and north Victoria Land, Antarctica. It is one of the two major dinosaur-bearing rock groups found on Antarctica to date; the other is the Snow Hill Island Formation and related formations from the Late Cretaceous of the Antarctic Peninsula. The formation has yielded some Mesozoic specimens, but most of it is as yet unexcavated. Part of the Victoria Group of the Transantarctic Mountains, it lies below the Prebble Formation and above the Falla Formation. The formation includes material from volcanic activity linked to the Karoo-Ferar eruptions of the Lower Jurassic. The climate of the zone was similar to that of modern southern Chile, humid, with a temperature interval of 17–18 degrees. The Hanson Formation is correlated with the Section Peak Formation of the Eisenhower Range and Deep Freeze Range, as well as volcanic deposits on the Convoy Range and Ricker Hills of southern Victoria Land. Recent work has successfully correlated the Upper Section Peak Formation, as well unnamed deposits in Convoy Range and Ricker Hills with the Lower Hanson, all likely of Sinemurian age and connected by layers of silicic ash, while the upper section has been found to be Pliensbachian, and correlated with a greater volcanic pulse, marked by massive ash inputs.
The Karoo and Ferrar Large Igneous Provinces (LIPs) are two large igneous provinces in Southern Africa and Antarctica respectively, collectively known as the Karoo-Ferrar, Gondwana, or Southeast African LIP, associated with the initial break-up of the Gondwana supercontinent at c.183Ma. Its flood basalt mostly covers South Africa and Antarctica but portions extend further into southern Africa and into South America, India, Australia and New Zealand.
Glacialisaurus is a genus of sauropodomorph dinosaur from the Early Jurassic period of Antarctica. It is known from two specimens; the holotype, a partial tarsus (ankle) and metatarsus, and a partial left femur. The fossils were collected by a team led by paleontologist William R. Hammer during a 1990–91 field expedition to the central region of the Transantarctic Mountains. They come from sedimentary rocks of the Hanson Formation and date to the Pliensbachian stage of the Early Jurassic, around 186 to 182 million years ago. The fossils were described in 2007, and made the basis of the new genus and species Glacialisaurus hammeri. The genus name translates as “icy” or "frozen lizard”, and the specific name honors Hammer.
The Beacon Supergroup is a geological formation exposed in Antarctica and deposited from the Devonian to the Triassic. The unit was originally described as either a formation or sandstone, and upgraded to group and supergroup as time passed. It contains a sandy member known as the Beacon Heights Orthoquartzite.
Diplurus is a genus of prehistoric mawsoniid coelacanth fish which lived during the Late Triassic-Early Jurassic period in North America. The fossils of this genus are common on the eastern North American Margin, being a key taxon of the Newark Supergroup, and recovered from units such as the Bull Run Formation, Lockatong Formation, Stockton Formation, Solite Quarry, Midland Formation, East Berlin Formation, Boonton Formation and the Portland Formation. Three species are know, the type D. longicaudatus, the youngest and biggest, D. newarki, the oldest, followed then by "D. uddeni" (Eastman), also from older rocks and considered dubious. A recent work has recovered a 3rd or 4th species, D. enigmaticus, from the Late Triassic of New Jersey, representing another small-bodied form living in sympatry with the similarly sized D. newarki. This genus ranges in size from 15 cm of D. newarki and D. enigmaticus in New Jersey to the larger 60 cm specimens of Diplurus longicaudatus found in the Connecticut River Valley, which indicates a considerable growth and likely a change in the ecological position of the genus to a possible apex predatory niche.
Aphnelepis is an extinct genus of prehistoric freshwater ray-finned fish that lived during the Late Jurassic epoch. It contains a single species, A. australis, from the Talbragar River beds of New South Wales, Australia.
Wadeichthys oxyops is an extinct archaeomaenid bony fish from the Koonwarra Lake fauna of Lower Cretaceous Victoria, Australia. If the related genus Koonwarria is regarded as being in a different family, then W. oxyops is the only known Cretaceous-aged archaeomaenid from Australia.
Cavenderichthys is an extinct genus of prehistoric freshwater ray-finned fish from the Late Jurassic. It contains a single species, C. talbragarensis from the Talbragar Fish beds of New South Wales, Australia.
The Cañadón Asfalto Formation is a geological formation from the Lower Jurassic, with doubtful layers of Late Jurassic age previously referred to it. The Cañadón Asfalto Formation is located in the Cañadón Asfalto Basin, a rift basin in the Chubut Province of northwestern Patagonia, southern Argentina. The basin started forming in the earliest Jurassic.
Carapace Nunatak is a prominent isolated nunatak, the most westerly near the head of Mackay Glacier in Victoria Land, standing 8 nautical miles (15 km) southwest of Mount Brooke where it is visible for a considerable distance from many directions. It was so named by the New Zealand party of the Commonwealth Trans-Antarctic Expedition (1956–1958) because of the fossil carapaces of small crustaceans found in the exposed rocks.
The East Antarctic Shield or Craton is a cratonic rock body that covers 10.2 million square kilometers or roughly 73% of the continent of Antarctica. The shield is almost entirely buried by the East Antarctic Ice Sheet that has an average thickness of 2200 meters but reaches up to 4700 meters in some locations. East Antarctica is separated from West Antarctica by the 100–300 kilometer wide Transantarctic Mountains, which span nearly 3,500 kilometers from the Weddell Sea to the Ross Sea. The East Antarctic Shield is then divided into an extensive central craton that occupies most of the continental interior and various other marginal cratons that are exposed along the coast.
Archaeomaenidae is an extinct family of stem-teleost fish found in freshwater environments of Jurassic New South Wales of Australia, China, and Antarctica, and in Lower Cretaceous New South Wales and Mongolia.
The Chon Aike Formation is an extensive geological formation, present in the Deseado Massif in north-central Santa Cruz Province, Patagonia, Argentina. It covers an area of approximately 100,000 square kilometres (39,000 sq mi) and consists of rhyolitic volcanic rocks, particularly ignimbrites and lavas, with smaller amounts of agglomerates and tuffs. Within dacitic rocks, plant fossils have been found.
The geology of Saudi Arabia includes Precambrian igneous and metamorphic basement rocks, exposed across much of the country. Thick sedimentary sequences from the Phanerozoic dominate much of the country's surface and host oil.
The Mawson Formation is a geological formation in Antarctica, dating to roughly between 182 and 177 million years ago and covering the Toarcian stages of the Jurassic Period in the Mesozoic Era. Vertebrate remains are known from the formation. The Mawson Formation is the South Victoria Land equivalent of the Karoo Large Igneous Province in South Africa, as well the Lonco Trapial Formation and the Cañadón Asfalto Formation of Argentina. The Volcanic material was likely sourced from the Antarctic Peninsula´s Ellsworth Land Volcanic Group.
Asfaltovenator is a genus of possibly allosauroid dinosaur from the Lower Jurassic Cañadón Asfalto Formation of Chubut Province, Argentina. The type and only species is Asfaltovenator vialidadi.
The Djupadal Formation is a geologic formation in Skåne County, southern Sweden. It is Early Jurassic in age. It is part of the Central Skåne Volcanic Province, know by the discovery of basalt tuff layers, including Sandåkra, Korsaröd and Djupadal.
The Ellsworth Land Volcanic Group is a geological formation in the Latady Basin, Ellsworth Land, Antarctic Peninsula, with a calculated maximum depositional age of 183.4 ± 1.4 Ma, and a younger age around 177.5 ± 2.2 Ma, covering the Toarcian stage of the Jurassic Period in the Mesozoic Era. This group is made up of volcanoclastic material, with the Mount Poster Formation, composed of silicic ignimbrites, and the Sweeney Formation, consisting of a mix of basaltic and sedimentary facies.