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Chañares Formation
The Chañares Formation is a Carnian-age geologic formation of the Ischigualasto-Villa Unión Basin, located in La Rioja Province, Argentina. It is characterized by drab-colored fine-grained volcaniclastic claystones, siltstones, and sandstones which were deposited in a fluvial to lacustrine environment. The formation is most prominently exposed within Talampaya National Park, a UNESCO World Heritage Site within La Rioja Province. The Chañares formation is the lowermost stratigraphic unit of the Agua de la Peña Group, overlying the Tarjados Formation of the Paganzo Group, and underlying the Los Rastros Formation. Though previously considered Ladinian in age, U-Pb dating has determined that most or all of the Chañares Formation dates to the early Carnian stage of the Late Triassic.Kent et al, 2014, p.7959 The Chañares Formation has provided a diverse and well-preserved faunal assemblage which has been studied intensively since the 1960s. The most common reptiles were pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geologic 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 exposed in a geographical region (the stratigraphic column). It is the fundamental unit of lithostratigraphy, the study of strata or rock layers. A formation must be large enough that it can be mapped at the surface or traced in the subsurface. Formations are otherwise not defined by the thickness of their rock strata, which can vary widely. They are usually, but not universally, tabular in form. They may consist of a single lithology (rock type), or of alternating beds of two or more lithologies, or even a heterogeneous mixture of lithologies, so long as this distinguishes them from adjacent bodies of rock. The concept of a geologic formation goes back to the beginnings of modern scientific geology. The term was used by Abraham Gottlob ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Claystone
Mudrocks are a class of fine-grained siliciclastic sedimentary rocks. The varying types of mudrocks include siltstone, claystone, mudstone, slate, and shale. Most of the particles of which the stone is composed are less than and are too small to study readily in the field. At first sight, the rock types appear quite similar; however, there are important differences in composition and nomenclature. There has been a great deal of disagreement involving the classification of mudrocks. A few important hurdles to their classification include the following: # Mudrocks are the least understood and among the most understudied sedimentary rocks to date. # Studying mudrock constituents is difficult due to their diminutive size and susceptibility to weathering on outcrops. # And most importantly, scientists accept more than one classification scheme. Mudrocks make up 50% of the sedimentary rocks in the geologic record and are easily the most widespread deposits on Earth. Fine sedimen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Archosaur
Archosauria () is a clade of diapsids, with birds and crocodilians as the only living representatives. Archosaurs are broadly classified as reptiles, in the cladistic sense of the term which includes birds. Extinct archosaurs include non-avian dinosaurs, pterosaurs, and extinct relatives of crocodilians. Modern paleontologists define Archosauria as a crown group that includes the most recent common ancestor of living birds and crocodilians, and all of its descendants. The base of Archosauria splits into two clades: Pseudosuchia, which includes crocodilians and their extinct relatives, and Avemetatarsalia, which includes birds and their extinct relatives (such as non-avian dinosaurs and pterosaurs). Older definitions of the group Archosauria rely on shared morphological characteristics, such as an antorbital fenestra in the skull, serrated teeth, and an upright stance. Some extinct reptiles, such as proterosuchids and euparkeriids, possessed these features yet orig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gualosuchus
''Gualosuchus'' is an extinct genus of proterochampsian archosauriform from the Middle Triassic Chañares Formation of Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th .... The type and only species is ''Gualosuchus reigi'', named by paleontologist Alfred Romer in 1971. References Proterochampsians Middle Triassic reptiles of South America Triassic Argentina Fossils of Argentina Chañares Formation Fossil taxa described in 1971 Taxa named by Alfred Romer Prehistoric reptile genera {{Triassic-reptile-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tropidosuchus
''Tropidosuchus'' is an extinct genus of carnivorous archosauriforms from the Middle Triassic period (Anisian to Ladinian stage). It is a proterochampsid which lived in what is now Argentina. It is known from the holotype PVL 4601, which consists of partial skeleton. It was found in the Chañares Formation and its type locality is the Chañares River. It was first named by A. B. Arcucci in 1990 and the type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ... is ''Tropidosuchus romeri''. References Proterochampsians Ladinian genera Middle Triassic reptiles of South America Triassic Argentina Fossils of Argentina Chañares Formation Fossil taxa described in 1990 Prehistoric reptile genera {{triassic-reptile-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chanaresuchus
''Chanaresuchus'' is an extinct genus of proterochampsian archosauriform. It was of modest size for a proterochampsian, being on average just over a meter in length. Fossils are known from the Middle and Late Triassic of La Rioja Province, Argentina and Rio Grande do Sul (geoparque Paleorrota), Brazil. The type species and only currently known species is ''Chanaresuchus bonapartei'' was named from the Ladinian-age Chañares Formation in 1971. A second species ''C. ischigualastensis'' named in 2012 from the late Carnian-age Ischigualasto Formation, was briefly assigned to ''Chanaresuchus'' before being moved to its own genus '' Pseudochampsa'' in 2014. ''C. bonapartei'' has recently been found in the Carnian Santa Maria Formation in Brazil. ''Chanaresuchus'' appears to be one of the most common archosauriforms from the Chanares Formation due to the abundance of specimens referred to the genus. Much of the material has been found by the La Plata-Harvard expedition of 1964-65. ''Cha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proterochampsidae
Proterochampsidae is a family of proterochampsian archosauriforms. Proterochampsids may have filled an ecological niche similar to modern crocodiles, and had a general crocodile-like appearance. They lived in what is now South America in the Middle and Late Triassic. Description Proterochampsids have long, crocodile-like skulls. The posterior portion of the skull is wide while the snout is very narrow. Most proterochampsids also have downturned snouts. Like many early archosauriforms, they also have dermal armour. Proterochampsids have small holes called dorsal fenestrae at the top of their skulls. Unlike other early archosauromorphs, they do not have a parietal foramin, which in many reptiles holds a parietal eye. The postorbital bones behind the eye sockets have thick, jagged crests. As another diagnostic feature of the group, the holes that allow the passage of the internal carotid artery through the braincase open at the sides of a bony projection called the basipterygoid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
