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Valle Alto Formation
The Valle Alto Formation ( es, Formación Valle Alto, Jva) is a geological formation of the Central Ranges of the Colombian Andes. The formation is composed of shales, sandstones and conglomerates and dates to the Late Jurassic period. Ammonites and fossil flora have been found in the Valle Alto Formation. Etymology The formation was described and named in 1977 by González et al. after Hacienda Valle Alto, San Félix, Caldas.Moreno Sánchez et al., 2007Mojica, 1984, p.132 Lithologies The Valle Alto Formation is composed of shales, sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates ...s and conglomerates.Isagen, 2009, p.9 Stratigraphy, age and depositional environment The Valle Alto Formation, part of the Quebradagrande Complex, is not defined as a proper forma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Late Jurassic
The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 163.5 ± 1.0 to 145.0 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic strata.Owen 1987. In European lithostratigraphy, the name "Malm" indicates rocks of Late Jurassic age. In the past, ''Malm'' was also used to indicate the unit of geological time, but this usage is now discouraged to make a clear distinction between lithostratigraphic and geochronologic/chronostratigraphic units. Subdivisions The Late Jurassic is divided into three ages, which correspond with the three (faunal) stages of Upper Jurassic rock: Paleogeography During the Late Jurassic Epoch, Pangaea broke up into two supercontinents, Laurasia to the north, and Gondwana to the south. The result of this break-up was the spawning of the Atlantic Ocean. However, at this time, the Atlantic Ocean was relatively narrow. Life forms of the epoch This epoch is well known for many famous types of dinosau ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sagenopteris
''Sagenopteris'' is a genus of extinct seed ferns from the Triassic to late Early Cretaceous.''Sagenopteris'' at Fossilworks.org Description ''Sagenopteris'' has palmately arranged leaves with anastomosing venation. Different organs attributed to the same original plant can be reconstructed from co-occurrence at the same locality and from similarities in the stomatal apparatus and other anatomical peculiarities of fossilized cuticles. * '''' may have been produced by the same plant as '' |
Ptilophyllum
''Ptilophyllum'' is an extinct form genus of leaves belonging to the extinct seed plant order Bennettitales. The leaves, like other Bennettitales morphogenera are generally pinnate Pinnation (also called pennation) is the arrangement of feather-like or multi-divided features arising from both sides of a common axis. Pinnation occurs in biological morphology, in crystals, such as some forms of ice or metal crystals, and in .... Leaves possibly attributable to the genus are known from the Oligocene of Australia, which may be the last known representatives of the order. References Prehistoric plant genera Bennettitales Triassic plants Jurassic plants Cretaceous plants Fossil taxa described in 1840 Prehistoric plants of North America {{cretaceous-plant-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pachypteris
''Pachypteris'' ( Brongn.) T.M.Harris. is a Mesozoic pteridosperm leaf fossil probably belonging to the seed fern Order Peltaspermales. Description ''Pachypteris'' is represented by hypostomatic, bipinnate or unipinnate leaves, with alethopteridian venation (midvein and secondary veins divided once or twice before reaching the pinnule margin), pinnules with entire margins and rounded apices. The stomata are haplocheilic, monocyclic or dicyclic, usually depressed, with the guard cells occurring in the lowermost part of the stoma. Taxonomy The affinities of ''Pachypteris'' lay with '' Cycadopteris'', '' Komlopteris'', ''Dicroidium'' (a typical Corystospermalean foliage) and '' Ptilozamites''. It includes the former denomination ''Thinnfeldia'' Ettingshausen 1852, a junior synonym of ''Pachypteris'', as Doludenko (1971) showed. The genus was detailed by Harris (1964), Doludenko (1974), Schweitzer and Kirchner (1998), Popa (2000), and Gordenko (2007). The genus ''Komlopteris'', ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Otozamites
''Otozamites'' is an extinct form genus Form classification is the classification of organisms based on their morphology, which does not necessarily reflect their biological relationships. Form classification, generally restricted to palaeontology, reflects uncertainty; the goal of s ... of leaves belonging to the Bennettitales. ''Otozamites'' are an extinct form genus of leaves related to the Bennettitales. Most of the ''Otozamites'' leaves are secluded and conserved as pinnae. Leaflet of ''Otozamites'' have the shape of an elongated triangular shape with an acute apex. ''Otozamites'' pinnae that emerge from the rachis has never been recorded ever before in the history of the organism, worldwide. References 4. Wang, Y. D., Ni, Q., Jiang, Z. K., & Tian, N. (2008). Diversity variation and tempo-spatial distribution of Otozamites (Bennettitales) in the Mesozoic of China. ''Palaeoworld'', ''17''(3-4), 222–234. 5. Barale, G. (1987). New observations on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nilssoniopteris
''Nilssoniopteris'' is an extinct form genus of leaves belonging to the Bennettitales. Leaves are slender and often entire-margined (smooth-edged), though some species have dissected leaves with numerous small segments extending down to the rachis of the leaf. ''Nilssoniopteris''-like leaves are distinguished by their syndetocheilic stomata, indicating bennettitalean affinities. Similar "taeniopterid" leaves are placed in the genus '' Nilssonia'' if their stomata are instead haplocheilic (indicating cycad affinities), or '' Taeniopteris'' if the cuticle A cuticle (), or cuticula, is any of a variety of tough but flexible, non-mineral outer coverings of an organism, or parts of an organism, that provide protection. Various types of "cuticle" are non- homologous, differing in their origin, structu ... is not preserved. References Prehistoric plant genera Bennettitales Permian plants Triassic plants Jurassic plants Cretaceous plants Prehistoric plants of North Ameri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
