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Preprismatoolithus
''Preprismatoolithus'' is a Late Jurassic oogenus. The species ''P. coloradensis'' is described by John Foster as being "of the prismatic basic type," with subspherical eggs about 10 cm (4 inches) in diameter."Eggs," Foster (2007) page 125. This oospecies has been initially attributed to "hypsilophodontid" dinosaurs, although a lack of associated embryo material currently makes confirming the egg-layer's identity impossible,"Another Generation: The Eggs," Foster (2007) page 239. but now is known to be theropod after the finding in Portugal,Ribeiro, V., Mateus O., Holwerda F., Araújo R., & Castanhinha R. (2013). Two new theropod egg sites from the Late Jurassic Lourinhã Formation, Portugal. Historical Biology. (ahead-of-print), 1-12. associated with the embryos. Eggshell present in great abundance at the so-called "Young Egg Locality" which seems to have been a dinosaur nesting ground. Congeneric eggshell fossils are found at additional Colorado sites including the F ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Egg Fossil
Egg fossils are the fossilized remains of eggs laid by ancient animals. As evidence of the physiological processes of an animal, egg fossils are considered a type of trace fossil. Under rare circumstances a fossil egg may preserve the remains of the once- developing embryo inside, in which case it also contains body fossils. A wide variety of different animal groups laid eggs that are now preserved in the fossil record beginning in the Paleozoic. Examples include invertebrates like ammonoids as well as vertebrates like fishes, possible amphibians, and reptiles. The latter group includes the many dinosaur eggs that have been recovered from Mesozoic strata. Since the organism responsible for laying any given egg fossil is frequently unknown, scientists classify eggs using a parallel system of taxonomy separate from but modeled after the Linnaean system. This "parataxonomy" is called ''veterovata''. History The first named oospecies was '' Oolithes bathonicae'', a name given provis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dinosaurs Of The Morrison Formation
The Morrison Formation is a distinctive sequence of Upper Jurassic sedimentary rock that is found in the western United States, which has been the most fertile source of dinosaur fossils in North America. It is composed of mudstone, sandstone, siltstone and limestone and is light grey, greenish gray, or red. Most of the fossils occur in the green siltstone beds and lower sandstones, relics of the rivers and floodplains of the Jurassic period. Fauna comparisons The fauna of Morrison Formation is similar to one in the coeval rocks of Tendaguru Beds (in Tanzania) and Lourinhã Formation in Portugal, mostly with the second. Some genera are shared in Morrison and Lourinhã, such as ''Torvosaurus'', ''Ceratosaurus'', ''Stegosaurus'', ''Dryosaurus'', and ''Allosaurus''.Mateus, O, Walen A, Antunes MT. 2006. The large theropod fauna of the Lourinhã Formation (Portugal) and its similarity to the Morrison Formation, with a description of a new species of Allosaurus. New Mexico Museum ... [...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] |
Hypsilophodont
Hypsilophodontidae (or Hypsilophodontia) is a traditionally used family of ornithopod dinosaurs, generally considered invalid today. It historically included many small bodied bipedal neornithischian taxa from around the world, and spanning from the Middle Jurassic until the Late Cretaceous. This inclusive status was supported by some phylogenetic analyses from the 1990s and mid 2000s, although there have also been many finding that the family is an unnatural grouping which should only include the type genus, ''Hypsilophodon'', with the other genera being within clades like Thescelosauridae and Elasmaria. A 2014 analysis by Norman recovered a grouping of ''Hypsilophodon'', Rhabdodontidae and ''Tenontosaurus'', which he referred to as Hypsilophodontia. All other analyses from around the same time have instead found these latter taxa to be within Iguanodontia. Linnaean usage Hypsilophodontidae was named originally in 1882 by Louis Dollo, as a family to include ''Hypsilophodon'' a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dinosaur Trace Fossils
Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is the subject of active research. They became the dominant terrestrial vertebrates after the Triassic–Jurassic extinction event 201.3 mya; their dominance continued throughout the Jurassic and Cretaceous periods. The fossil record shows that birds are feathered dinosaurs, having evolved from earlier theropods during the Late Jurassic epoch, and are the only dinosaur lineage known to have survived the Cretaceous–Paleogene extinction event approximately 66 mya. Dinosaurs can therefore be divided into avian dinosaurs—birds—and the extinct non-avian dinosaurs, which are all dinosaurs other than birds. Dinosaurs are varied from taxonomic, morphological and ecological standpoints. Birds, at over 10,700 living species, are among th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
