Santana Group | |
---|---|
Stratigraphic range: Aptian-Albian ~ | |
Type | Group |
Sub-units | Romualdo, Ipubi & Crato Formations |
Underlies | Araripina & Exu Formations |
Overlies | Barbalha Formation |
Lithology | |
Primary | Mudstone, sandstone, shale, anhydrite |
Other | Limestone, marl, siltstone |
Location | |
Coordinates | 5°36′S64°18′W / 5.6°S 64.3°W |
Approximate paleocoordinates | 9°12′S34°00′W / 9.2°S 34.0°W |
Region | Pernambuco Piauí Ceará |
Country | Brazil |
Extent | Araripe Basin |
Type section | |
Named for | Santana do Cariri |
Extent of the Santana Group in blue |
The Santana Group is a geologic group, formerly included as the middle part of the Araripe Group, in the Araripe Basin of northeastern Brazil. The group comprises the Crato, Ipubi and Romualdo Formations and is dated to the Aptian to Albian stages of the Early Cretaceous. The formations of the group were deposited in a lacustrine to subtidal shallow marine environment in the Araripe rift basin. [1]
The Santana Group has provided a rich assemblage of fossils; flora, fish, arthropods insects, turtles, snakes, dinosaurs including Irritator , and pterosaurs such as Thalassodromeus . The stratigraphic units of the group contained several feathers of birds, among those the first record of Mesozoic birds in Brazil. The Romualdo and Crato Formations are renowned for their excellent conservation and designated Lagerstätten. In 2006, the Araripe Basin was designated a UNESCO Global Geopark.
The Santana Group was formerly described as belonging to the Araripe Group. [2] The fossiliferous Santana Formation was previously defined as containing the Crato and Romualdo Members, but redefinition of the stratigraphy led to the establishment of the Santana Group, replacing the middle part of the Araripe Group and the former Crato, Ipubi and Romualdo members were elevated to separate formations. [3] [4]
The tectono-sedimentary evolution of the Araripe Basin, located in the Borborema Geologic Province, encompasses four stages, with five tectonostratigraphic phases: [5]
1) Syneclise phase - Silurian to Devonian - characterized by tectonic quiescence in the Borborema Province. It is represented by the deposits of the Cariri Formation, that include medium to coarse-grained quartz sandstones, locally conglomeratic, deposited in large braided fluvial systems
2) Pre-rift phase - Tithonian - characterized by the mechanical subsidence due to lithosphere thinning that preceded the rift. It is represented by the Brejo Santo Formation, that comprises red shales and claystones, and the Missão Velha Formation, constituted by medium to coarse-grained quartz-feldspathic sandstones, locally conglomeratic, that contains entire trunks and fragments of silicified wood ( Dadoxilon benderi ) conifer
3) Rift phase - Berriasian to Hauterivian - characterized by increasing mechanical subsidence that created a system of grabens and half grabens. It is represented by the Abaiara Formation, that includes shales, siltstones, sandstones and conglomerates
4) Post-Rift I phase - Aptian to Albian - characterized by thermal subsidence. The lowermost unit Barbalha Formation, represents a fluviolacustrine phase and is composed of red and gray shales, siltstones and claystones.
The Santana Group was formed during this stage and comprises three stratigraphic units:
5) Post-rift II phase - Albian to Cenomanian - characterized by a major sag phase, and is formed by two stratigraphic units:
The upper and lower formations of the group are highly fossiliferous, with mainly insects, amphibians, fish, [6] [7] and flora dominating the lower Crato Formation, [8] shrimps ( Araripenaeus timidus ), [9] and various genera of dinosaurs and fish in the Romualdo Formation. [10] [11] A rich assemblage of pterosaur fossils are found in both formations, [12] [13] and the Ipubi Formation provided an indeterminate Pelomedusoides turtle. [14]
The Santana Group provided several feathers of birds, among those the first record of Mesozoic birds in Brazil. [15]
The Crato Formation is a geologic formation of Early Cretaceous (Aptian) age in northeastern Brazil's Araripe Basin. It is an important Lagerstätte for palaeontologists. The strata were laid down mostly during the Aptian age, about 113 million years ago. It thought to have been deposited in a semi-arid lacustrine wetland environment.
Irritator is a genus of spinosaurid dinosaur that lived in what is now Brazil during the Albian stage of the Early Cretaceous Period, about 113 to 110 million years ago. It is known from a nearly complete skull found in the Romualdo Formation of the Araripe Basin. Fossil dealers had acquired this skull and sold it to the State Museum of Natural History Stuttgart. In 1996, the specimen became the holotype of the type species Irritator challengeri. The genus name comes from the word "irritation", reflecting the feelings of paleontologists who found the skull had been heavily damaged and altered by the collectors. The species name is a homage to the fictional character Professor Challenger from Arthur Conan Doyle's novels.
The Romualdo Formation is a geologic Konservat-Lagerstätte in northeastern Brazil's Araripe Basin where the states of Pernambuco, Piauí and Ceará come together. The geological formation, previously designated as the Romualdo Member of the Santana Formation, named after the village of Santana do Cariri, lies at the base of the Araripe Plateau. It was discovered by Johann Baptist von Spix in 1819. The strata were deposited during the Aptian stage of the Early Cretaceous in a lacustrine rift basin with shallow marine incursions of the proto-Atlantic. At that time, the South Atlantic was opening up in a long narrow shallow sea.
Tupuxuara is a genus of large, crested, and toothless pterodactyloid pterosaur from the Early Cretaceous period of what is now the Romualdo Formation of the Santana Group, Brazil, about 125 to 112 million years ago. Tupuxuara is a close relative of Thalassodromeus, and both form a group that is either called Thalassodrominae or Thalassodromidae.
Thalassodromeus is a genus of pterosaur that lived in what is now Brazil during the Early Cretaceous period, about a hundred million years ago. The original skull, discovered in 1983 in the Araripe Basin of northeastern Brazil, was collected in several pieces. In 2002, the skull was made the holotype specimen of Thalassodromeus sethi by palaeontologists Alexander Kellner and Diogenes de Almeida Campos. The generic name means "sea runner", and the specific name refers to the Egyptian god Seth due to its crest being supposedly reminiscent of Seth's crown. Other scholars have pointed out that the crest was instead similar to the crown of Amon. A jaw tip was assigned to T. sethi in 2005, became the basis of the new genus Banguela in 2015, and assigned back to Thalassodromeus as the species T. oberlii in 2018, though other researchers consider it a valid genus. Another species was described in 2015 based on a supposed crest fragment, but this was later shown to be part of a turtle shell.
Anhanguera is a genus of pterodactyloid pterosaur known from the Early Cretaceous Romualdo Formation of Brazil and the Late Cretaceous Kem Kem Group of Morocco. This pterosaur is closely related to Ornithocheirus, but belongs in the family Anhangueridae. The generic name comes from the Tupi words añanga, meaning "spirit protector of the animals" + wera "bygone".
Brasileodactylus a genus of pterosaur from the Aptian-age lower Santana formation of Chapada do Araripe, Ceará, Brazil.
Axelrodichthys is an extinct genus of mawsoniid coelacanth from the Cretaceous of Africa, North and South America, and Europe. Several species are known, the remains of which were discovered in the Lower Cretaceous (Aptian-Albian) of Brazil, North Africa, and possibly Mexico, as well as in the Upper Cretaceous of Morocco (Cenomanian), Madagascar and France. The Axelrodichthys of the Lower Cretaceous frequented both brackish and coastal marine waters while the most recent species lived exclusively in fresh waters. The French specimens are the last known fresh water coelacanths. Most of the species of this genus reached 1 metre to 2 metres in length. Axelrodichthys was named in 1986 by John G. Maisey in honor of the American ichthyologist Herbert R. Axelrod.
Cladocyclus is an extinct genus of marine ichthyodectiform fish from the middle Cretaceous. It was a predatory fish of about 1.20 metres (3.9 ft) in length.
Santanichthys diasii is a species of extinct fish that existed around 115 million years ago during the Albian age. S. diasii is regarded as the basal-most characiform, and is the earliest known member of Otophysi. It appears as a small fish, similar in appearance to a modern-day herring little more than 30 millimeters in length. Its most striking characteristic is the presence of a Weberian apparatus, which makes it the most primitive known member of the order Characiformes, the order in which modern-day tetras are classified. Santanichthys has been unearthed from numerous locations throughout Brazil, in rocks dating to the Cretaceous Period. Its presence in these strata is seen as an indicator for the biogeography and evolution of its order.
Unwindia is a genus of pterodactyloid pterosaur from the Early Cretaceous period of what is now modern-day Brazil.
Banguela is a genus of azhdarchoid pterosaur from the Early Cretaceous period of what is now Brazil. Only one species is known, Banguela oberlii.
The Exu Formation is an Albian geologic formation in Brazil. Pterosaur fossils of Lophocratia indet. have been recovered from the formation.
Maaradactylus is a genus of anhanguerid pterodactyloid pterosaur known from the Lower Cretaceous period of the Romualdo Formation of northeastern Brazil.
Araripenymphes is an extinct genus of lacewing in the family Nymphidae known from fossils found in the Crato Formation of the Araripe Basin in South America. The genus contains a single species, Araripenymphes seldeni. The genus was named after the basin.
The Araripe Basin is a rift basin covering about 8,000 square kilometres (3,100 sq mi), in Ceará, Piauí and Pernambuco states of northeastern Brazil. It is bounded by the Patos and Pernambuco lineaments, and is situated east of the Parnaíba Basin, southwest of the Rio do Peixe Basin and northwest of the Tucano and Jatobá Basins.
Ornithocheiromorpha is a group of pterosaurs within the suborder Pterodactyloidea. Fossil remains of this group date back from the Early to Late Cretaceous periods, around 140 to 92.5 million years ago. Ornithocheiromorphs were discovered worldwide except Antarctica, though most genera were recovered in Europe, Asia and South America. They were the most diverse and successful pterosaurs during the Early Cretaceous, but throughout the Late Cretaceous they were replaced by pteranodontians and azhdarchoids. The Ornithocheiromorpha was defined in 2014 by Andres and colleagues, and they made Ornithocheiromorpha the most inclusive clade containing Ornithocheirus, but not Pteranodon.
The Ipubi Formation is the middle geological formation of the Santana Group, the middle part of the Araripe Group, in the Araripe Basin of northeastern Brazil. The formation is dated to the Aptian to Albian stages of the Early Cretaceous, unconformably overlying the Crato Formation and unconformably overlain by the Romualdo Formation, formerly known as the Romualdo Member of the Santana Formation. The averaging 15 metres (49 ft) thick Ipubi Formation comprises shales and sandstones in the lower section and evaporites in the upper part of the formation, deposited in a transgressive to highstand lacustrine environment in the Araripe rift basin.
The Missão Velha Formation is a late Jurassic geologic formation in northeastern Brazil's Araripe Basin where the states of Pernambuco, Piauí and Ceará come together. The formation is the middle stratigraphic unit of the Vale do Carirí Group, overlying the Brejo Santo Formation and overlain by the Abaiara Formation.
Aratasaurus is an extinct genus of basal coelurosaurian theropod dinosaur from the Early Cretaceous (Aptian) Romualdo Formation of Brazil. The genus contains a single species, A. museunacionali, known from a partial right leg. Aratasaurus represents the only tetrapod fossil known from the lower levels of the Romualdo Formation.