| Mesodescolea Temporal range: | |
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| Genus: | Mesodescolea S.Archang. [1] |
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Mesodescolea is a genus of fossil foliage with uncertain affinities from the Early Cretaceous of Argentina [1] and Antarctica. [2] It includes only one species, Mesodescolea plicata.
The genus was first erected by Sergio Archangelsky based on material from the Aptian of the Anfiteatro de Ticó formation. [1] The name of the genus is dedicated to the naturalist Horacio Descole. Although it was originally compared to cycadalean genera such as Ctenis and Stangeria , its affinities were originally considered uncertain. Later reinvestigations and emendations cemented the view that Mesodescolea was a member of the Cycadales family Stangeriaceae. [3] [4] [5] Other authors have proposed that the genus represents a member of the angiosperms with affinities with the ANA grade or Chloranthaceae. [6]
The genus includes leaves with highly lobed-dissected margins. The venation is hierarchical, with the tertiary veins forming an irregular reticulum. Chloranthoid teeth are present in the margins. The cuticle shows laterocytic stomata, and is characterized by striae and perforated idioblasts.
Leaves of Mesodescolea are locally abundant in the deposits of the Anfiteatro de Ticó formation. They are found in association with Ruflorinia /Ktalenia and the conifer Brachyphyllum . The depositional environment is characterized by river deposits, and the fossils show little evidence of transport. [7]
The Zamiaceae are a family of cycads that are superficially palm or fern-like. They are divided into two subfamilies with eight genera and about 150 species in the tropical and subtropical regions of Africa, Australia and North and South America.
Pteridospermatophyta, also called "pteridosperms" or "seed ferns" are a polyphyletic grouping of extinct seed-producing plants. The earliest fossil evidence for plants of this type are the lyginopterids of late Devonian age. They flourished particularly during the Carboniferous and Permian periods. Pteridosperms declined during the Mesozoic Era and had mostly disappeared by the end of the Cretaceous Period, though Komlopteris seem to have survived into Eocene times, based on fossil finds in Tasmania.
Sparassodonta is an extinct order of carnivorous metatherian mammals native to South America, related to modern marsupials. They were once considered to be true marsupials, but are now thought to be a separate side branch that split before the last common ancestor of all modern marsupials. A number of these mammalian predators closely resemble placental predators that evolved separately on other continents, and are cited frequently as examples of convergent evolution. They were first described by Florentino Ameghino, from fossils found in the Santa Cruz beds of Patagonia. Sparassodonts were present throughout South America's long period of "splendid isolation" during the Cenozoic; during this time, they shared the niches for large warm-blooded predators with the flightless terror birds. Previously, it was thought that these mammals died out in the face of competition from "more competitive" placental carnivorans during the Pliocene Great American Interchange, but more recent research has showed that sparassodonts died out long before eutherian carnivores arrived in South America. Sparassodonts have been referred to as borhyaenoids by some authors, but currently the term Borhyaenoidea refers to a restricted subgroup of sparassodonts comprising borhyaenids and their close relatives.
Xenotarsosaurus is a genus of abelisaurid theropod dinosaur that lived during the Late Cretaceous of Argentina.
Unquillosaurus is a genus of possible maniraptoran or carnosaurian theropod dinosaur from the Late Cretaceous Los Blanquitos Formation of Salta Province, Argentina. The genus contains a single species, U. ceibalii, known only from a single fossilized pubis.
The Magallanes Basin or Austral Basin is a major sedimentary basin in southern Patagonia. The basin covers a surface of about 170,000 to 200,000 square kilometres and has a NNW-SSE oriented shape. The basin is bounded to the west by the Andes mountains and is separated from the Malvinas Basin to the east by the Río Chico-Dungeness High. The basin evolved from being an extensional back-arc basin in the Mesozoic to being a compressional foreland basin in the Cenozoic. Rocks within the basin are Jurassic in age and include the Cerro Toro Formation. Three ages of the SALMA classification are defined in the basin; the Early Miocene Santacrucian from the Santa Cruz Formation and Friasian from the Río Frías Formation and the Pleistocene Ensenadan from the La Ensenada Formation.
The Bajo Barreal Formation is a geological formation in the Golfo San Jorge Basin of Chubut and Santa Cruz, Argentina whose strata date back to the Middle Cenomanian to Late Turonian. The formation was first described by Teruggi & Rossetto in 1963. The sandstones, claystones, mudstones, conglomerates and tuff were deposited in a fluvial environment. The upper part of formation is laterally equivalent to the Yacimiento El Trébol and Meseta Espinosa Formation and the lower part to the Laguna Palacios, Cañadón Seco and Comodoro Rivadavia Formations. The Bajo Barreal Formation is a reservoir rock in the Golfo San Jorge Basin.
Drusilasaura is an extinct genus of possible lognkosaurian titanosaur sauropod dinosaur which lived during the late Cretaceous of Santa Cruz Province of southern Patagonia, Argentina.
Brachyphyllum is a form genus of fossil coniferous plant foliage. Plants of the genus have been variously assigned to several different conifer groups including Araucariaceae and Cheirolepidiaceae. They are known from around the globe from the Late Carboniferous to the Late Cretaceous periods. B. sattlerae was named after the fictional palaebotanist Ellie Sattler from the Jurassic Park franchise.
The Mata Amarilla Formation is a fossiliferous formation of the Austral Basin in southern Patagonia, Argentina. The formation consists of sediments deposited during the Middle Cenomanian, dated to 96.94 to 95.52 Ma. The middle section of the formation was previously considered to be the Pari Aike Formation.
Hegetotherium is an extinct genus of mammals from the Early to Middle Miocene of South America. Fossils of this genus have been found in the Cerro Bandera, Cerro Boleadoras, Chichinales, Collón Curá, Santa Cruz and Sarmiento Formations of Argentina, the Nazareno Formation of Bolivia, and the Galera and Río Frías Formations of Chile.
The Anfiteatro de Ticó Formation is a geological formation from the Deseado Massif in the province of Santa Cruz, Argentina.
Sergio Archangelsky was an Argentine paleobotanist and palynologist. He was a pioneer of modern paleobotany in Argentina, as well as of cuticular morphology and ultrastructure. He was also a corresponding member of the Argentine Academy of Science.
Ticoa is an extinct genus originally assigned to the Cycadales from the Early Cretaceous of Argentina, Chile, and Antarctica. Other authors view this genus as a member of the polyphyletic "seed ferns".
Ruflorinia is a genus of fossilized foliage from the Early Cretaceous of Argentina assigned to the order Caytoniales.
Mesosingeria is a genus of fossil foliage attributable to the Cycadales. This genus is found in Early Cretaceous rocks from Argentina.
Restrepophyllum is a genus of fossil foliage attributable to the Zamiaceae. This genus is found in Early Cretaceous rocks from Argentina.
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.
The Santa Cruz Formation is a geological formation in the Magallanes/Austral Basin in southern Patagonia in Argentina and in adjacent areas of Chile. It dates to the late Early Miocene epoch, and is contemporaneous with eponymous Santacrucian SALMA. The formation extends from the Andes to the Atlantic coast. In its coastal section it is divided into two members, the lower, fossil rich Estancia La Costa Member, which has a lithology predominantly consisting of tuffaceous deposits and fine grained sedimentary claystone and mudstone, and the upper fossil-poor Estancia La Angelina Member, which consists of sedimentary rock, primarily claystone, mudstone, and sandstone. The environment of deposition is interpreted to have been mostly fluvial, with the lowermost part of the Estancia La Costa Member being transitional between fluvial and marine conditions. The environment of the Estancia La Costa Member is thought to have been relatively warm and humid, but likely became somewhat cooler and drier towards the end of the sequence. The Santa Cruz Formation is known for its abundance of South American native ungulates, as well as an abundance of rodents, xenarthrans, and metatherians.
Yatenavis is an extinct genus of enantiornithine bird from the Late Cretaceous Chorrillo Formation of Santa Cruz Province, Argentina. The genus contains a single species, Y. ieujensis, known from a partial humerus.
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