Metatheria is a mammalian clade that includes all mammals more closely related to marsupials than to placentals. First proposed by Thomas Henry Huxley in 1880, it is a more inclusive group than the marsupials; it contains all marsupials as well as many extinct non-marsupial relatives. It is one of two groups placed in the clade Theria alongside Eutheria, which contains the placentals.
Ferugliotheriidae is one of three known families in the order Gondwanatheria, an enigmatic group of extinct mammals. Gondwanatheres have been classified as a group of uncertain affinities or as members of Multituberculata, a major extinct mammalian order. The best-known representative of Ferugliotheriidae is the genus Ferugliotherium from the Late Cretaceous epoch in Argentina. A second genus, Trapalcotherium, is known from a single tooth, a first lower molariform, from a different Late Cretaceous Argentinean locality. Another genus known from a single tooth, Argentodites, was first described as an unrelated multituberculate, but later identified as possibly related to Ferugliotherium. Finally, a single tooth from the Paleogene of Peru, LACM 149371, perhaps a last upper molariform, and a recent specimen from Mexico, may represent related animals.
The Maastrichtian is, in the International Commission on Stratigraphy (ICS) geologic timescale, the latest age of the Late Cretaceous Epoch or Upper Cretaceous Series, the Cretaceous Period or System, and of the Mesozoic Era or Erathem. It spanned the interval from 72.1 to 66 million years ago. The Maastrichtian was preceded by the Campanian and succeeded by the Danian.
The Danian is the oldest age or lowest stage of the Paleocene Epoch or Series, of the Paleogene Period or System, and of the Cenozoic Era or Erathem. The beginning of the Danian is at the Cretaceous–Paleogene extinction event 66 Ma. The age ended 61.6 Ma, being followed by the Selandian.
Madtsoia is an extinct genus of madtsoiid snakes. It is known from the Eocene of Argentina, the Paleocene of Brazil, the Late Cretaceous (Maastrichtian) of India, and the Late Cretaceous (Maastrichtian) of Madagascar. The type species was the largest with an estimated length of 9–10 m (30–33 ft), and the other three species were smaller. A 5.1 m (17 ft) long M. madagascariensis would have weighed 50 kg (110 lb), but an isolated specimen suggests that this species reached 8 m (26 ft) in maximum length.
Herpetotheriidae is an extinct family of metatherians, closely related to marsupials. Species of this family are generally reconstructed as terrestrial, and are considered morphologically similar to modern opossums. Fossils of herpetotheriids come from North America, Asia, Europe, Africa, and perhaps South America. The oldest representative is Maastrichtidelphys from the latest Cretaceous (Maastrichtian) of the Netherlands and the youngest member is Amphiperatherium from the Middle Miocene of Europe. The group has been suggested to be paraphyletic, with an analysis of petrosal anatomy finding that North American Herpetotherium was more closely related to marsupials than the European Peratherium and Amphiperatherium.
The La Colonia Formation is a geological formation in Argentina whose strata date back to the Late Cretaceous. Dinosaur remains are among the fossils that have been recovered from the formation.
The Tiupampan age is a period of geologic time within the Paleocene epoch of the Paleogene used more specifically with South American land mammal ages (SALMA). It is the oldest SALMA age and precedes the Peligran age.
The Santa Lucía Formation is a Maastrichtian to Paleocene (Danian) geologic formation in Bolivia. Fossil ornithopod tracks have been reported from the Cretaceous lower part of the formation. It is the type formation of the Tiupampan South American land mammal age.
The Malargüe Group is a group of geologic formations of the Neuquén Basin of the Mendoza, Neuquén, Río Negro and La Pampa Provinces in northern Patagonia, Argentina. The formations of the Malargüe Group range in age between the middle Campanian to Deseadan, an Oligocene age of the SALMA classification, straddling the Cretaceous–Paleogene boundary, about 79 million to 30 million years in age. The group overlies the older Neuquén Group, separated by an unconformity dated to 79 Ma. The rocks of the Malargüe Group comprise both marine and continental deposits which are over 400 m (1312 ft) thick in total.
Meretrix is a genus of edible saltwater clams, marine bivalve molluscs in the family Veneridae, the Venus clams. They appeared in the fossil record in the Cenomanian age.
The La Meseta Formation is a sedimentary sequence deposited during the Eocene on Seymour Island off the coast of the Antarctic Peninsula. It is noted for its fossils, which include both marine organisms and the only terrestrial vertebrate fossils from the Cenozoic of Antarctica.
The Golfo San Jorge Basin is a hydrocarbon-rich sedimentary basin located in eastern Patagonia, Argentina. The basin covers the entire San Jorge Gulf and an inland area west of it, having one half located in Santa Cruz Province and the other in Chubut Province. The northern boundary of the basin is the North Patagonian Massif while the Deseado Massif forms the southern boundary of the basin. The basin has largely developed under condition of extensional tectonics, including rifting.
The Cañadón Asfalto Basin is an irregularly shaped sedimentary basin located in north-central Patagonia, Argentina. The basin stretches from and partly covers the North Patagonian Massif in the north, a high forming the boundary of the basin with the Neuquén Basin in the northwest, to the Cotricó High in the south, separating the basin from the Golfo San Jorge Basin. It is located in the southern part of Río Negro Province and northern part of Chubut Province. The eastern boundary of the basin is the North Patagonian Massif separating it from the offshore Valdés Basin and it is bound in the west by the Patagonian Andes, separating it from the small Ñirihuau Basin.
The Lefipán Formation is a Maastrichtian to Danian, straddling the Cretaceous-Paleogene boundary, geologic formation of the Cañadón Asfalto Basin in Chubut Province, Patagonia, Argentina. The up to 380 metres (1,250 ft) thick stratigraphic unit comprises mudstones, sandstones, siltstones and conglomerates, sourced from the North Patagonian Massif and deposited in a deltaic to shallow marine environment with a strong tidal influence. The basin that in those times was connected to the widening South Atlantic Ocean with a seaway connection to the Austral Basin and possibly with the Pacific Ocean.
The Itaboraí Formation is a highly fossiliferous geologic formation and Lagerstätte of the Itaboraí Basin in Rio de Janeiro, southeastern Brazil. The formation reaching a thickness of 100 metres (330 ft) is the defining unit for the Itaboraian South American land mammal age (SALMA), dating to the Early Eocene, approximately 53 to 50 Ma.
The Laguna del Hunco Formation or Laguna del Hunco Tuff is a localized Early Eocene fossiliferous geological formation of the Cañadón Asfalto Basin in central Patagonia, Argentina. The 170 metres (560 ft) thick formation comprises tuffaceous mudstones and sandstones deposited in a crater lake environment and crops out at Laguna del Hunco in the northwestern Chubut Province.
The Maria Farinha Formation is a geological formation of the Parnaíba Basin in Pernambuco, northeastern Brazil whose strata date back to the Danian stage of the Paleocene, or Tiupampan in the SALMA classification.
Gypsonictops is an extinct genus of leptictidan mammals of the family Gypsonictopidae, which was described in 1927 by George Gaylord Simpson. Species in this genus were small mammals and the first representatives of the order Leptictida, that appeared during the Upper Cretaceous.
The Salamanca Formation is a geologic formation in the Golfo San Jorge Basin of central Patagonia that yields well-preserved, well-dated fossils from the early Paleocene. Studies of these fossils are providing new data on plant and animal diversity following the end-Cretaceous extinction event.
