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Twin Mountains Formation
The Twin Mountains Formation, also known as the Twin Mak Formation, is a sedimentary rock formation, within the Trinity Group, found in Texas of the United States of America. It is a terrestrial formation of Aptian age (Lower Cretaceous), and is notable for its dinosaur fossils. Dinosaurs from this formation include the large theropod ''Acrocanthosaurus'', the sauropod ''Sauroposeidon'', as well as the ornithopods ''Tenontosaurus'' and ''Convolosaurus''. It is the lowermost unit of the lower Cretaceous, lying unconformably on Carboniferous strata. It is overlain by the Glen Rose Formation. It is the lateral equivalent of the lower part of the Antlers Formation. Paleobiota * '' Acrocanthosaurus atokensis''Weishampel, David B; et al. (2004). "Dinosaur distribution (Early Cretaceous, North America)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. Pp. 553-556. . * Dromaeosauridae indet. * The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geological 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 Wer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sauroposeidon
''Sauroposeidon'' ( ; meaning "lizard earthquake god", after the Greek god Poseidon) is a genus of sauropod dinosaur known from several incomplete specimens including a bone bed and fossilized trackways that have been found in the U.S. states of Oklahoma, Wyoming, and Texas. The fossils were found in rocks dating from near the end of the Early Cretaceous (Aptian–early Albian), from about 113 to 110 million years ago, a time when sauropod diversity in North America had greatly diminished. It was the last known North American sauropod prior to an absence of the group on the continent of roughly 40 million years that ended with the appearance of ''Alamosaurus'' during the Maastrichtian. While the holotype remains were initially discovered in 1994, due to their unexpected age and unusual size they were initially misclassified as pieces of petrified wood. A more detailed analysis in 1999 revealed their true nature which resulted in a minor media frenzy, and formal publication of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iguanodontia
Iguanodontia (the iguanodonts) is a clade of herbivorous dinosaurs that lived from the Middle Jurassic to Late Cretaceous. Some members include ''Camptosaurus'', ''Dryosaurus'', ''Iguanodon'', ''Tenontosaurus'', and the hadrosaurids or "duck-billed dinosaurs". Iguanodontians were one of the first groups of dinosaurs to be found. They are among the best known of the dinosaurs, and were among the most diverse and widespread herbivorous dinosaur groups of the Cretaceous period. Classification Iguanodontia is often listed as an infraorder within a suborder Ornithopoda, though Benton (2004) lists Ornithopoda as an infraorder and does not rank Iguanodontia. Traditionally, iguanodontians were grouped into the superfamily Iguanodontoidea and family Iguanodontidae. However, phylogenetic studies show that the traditional "iguanodontids" are a paraphyletic grade leading up to the hadrosaurs (duck-billed dinosaurs). Groups like Iguanodontoidea are sometimes still used as unranked clades ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tenontosaurus Dossi
''Tenontosaurus'' ( ; ) is a genus of medium- to large-sized ornithopod dinosaur. It was a relatively medium sized ornithopod, reaching in length and in body mass. It had an unusually long, broad tail, which like its back was stiffened with a network of bony tendons. The genus is known from the late Aptian to Albian ages of the Early Cretaceous period sediments of western North America, dating between 115 and 108 million years ago. It contains two species, ''Tenontosaurus tilletti'' (described by John Ostrom in 1970) and ''Tenontosaurus dossi'' (described by Winkler, Murry, and Jacobs in 1997). Many specimens of ''T. tilletti'' have been collected from several geological formations throughout western North America. ''T. dossi'' is known from only a handful of specimens collected from the Twin Mountains Formation of Parker County, Texas. History of discovery The first ''Tenontosaurus'' fossil was found in Big Horn County, Montana by an American Museum of Natural Histo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sauroposeidon Proteles
''Sauroposeidon'' ( ; meaning "lizard earthquake god", after the Greek god Poseidon) is a genus of sauropod dinosaur known from several incomplete specimens including a bone bed and fossilized trackways that have been found in the U.S. states of Oklahoma, Wyoming, and Texas. The fossils were found in rocks dating from near the end of the Early Cretaceous (Aptian–early Albian), from about 113 to 110 million years ago, a time when sauropod diversity in North America had greatly diminished. It was the last known North American sauropod prior to an absence of the group on the continent of roughly 40 million years that ended with the appearance of ''Alamosaurus'' during the Maastrichtian. While the holotype remains were initially discovered in 1994, due to their unexpected age and unusual size they were initially misclassified as pieces of petrified wood. A more detailed analysis in 1999 revealed their true nature which resulted in a minor media frenzy, and formal publication of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sauropoda
Sauropoda (), whose members are known as sauropods (; from '' sauro-'' + '' -pod'', 'lizard-footed'), is a clade of saurischian ('lizard-hipped') dinosaurs. Sauropods had very long necks, long tails, small heads (relative to the rest of their body), and four thick, pillar-like legs. They are notable for the enormous sizes attained by some species, and the group includes the largest animals to have ever lived on land. Well-known genera include ''Brachiosaurus'', ''Diplodocus'', ''Apatosaurus'' and ''Brontosaurus''. The oldest known unequivocal sauropod dinosaurs are known from the Early Jurassic. ''Isanosaurus'' and ''Antetonitrus'' were originally described as Triassic sauropods, but their age, and in the case of ''Antetonitrus'' also its sauropod status, were subsequently questioned. Sauropod-like sauropodomorph tracks from the Fleming Fjord Formation (Greenland) might, however, indicate the occurrence of the group in the Late Triassic. By the Late Jurassic (150 million yea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theropoda
Theropoda (; ), whose members are known as theropods, is a dinosaur clade that is characterized by hollow bones and three toes and claws on each limb. Theropods are generally classed as a group of saurischian dinosaurs. They were ancestrally carnivorous, although a number of theropod groups evolved to become herbivores and omnivores. Theropods first appeared during the Carnian age of the late Triassic Period (geology), period 231.4 million years ago (Year#SI prefix multipliers, Ma) and included all the large terrestrial carnivores from the Early Jurassic until at least the close of the Cretaceous, about 66 Ma. In the Jurassic, birds evolved from small specialized coelurosaurian theropods, and are today represented by about 10,500 living species. Biology Diet and teeth Theropods exhibit a wide range of diets, from insectivores to herbivores and carnivores. Strict carnivory has always been considered the ancestral diet for theropods as a group, and a wider variety of di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dromaeosauridae
Dromaeosauridae () is a family of feathered theropod dinosaurs. They were generally small to medium-sized feathered carnivores that flourished in the Cretaceous Period. The name Dromaeosauridae means 'running lizards', from Greek ('), meaning 'runner', and ('), meaning 'lizard'. In informal usage, they are often called raptors (after ''Velociraptor''), a term popularized by the film '' Jurassic Park''; a few types include the term "raptor" directly in their name and have come to emphasize their bird-like appearance and speculated bird-like behavior. Dromaeosaurid fossils have been found across the globe in North America, Europe, Africa, Asia, South America and Antarctica, with some fossils giving credence to the possibility that they inhabited Australia as well. They first appeared in the mid-Jurassic Period (late Bathonian stage, about 167 million years ago) and survived until the end of the Cretaceous (Maastrichtian stage, 66 ma), existing until the Cretaceous–Paleogene ex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acrocanthosaurus Atokensis
''Acrocanthosaurus'' ( ; ) is a genus of carcharodontosaurid dinosaur that existed in what is now North America during the Aptian and early Albian stages of the Early Cretaceous, from 113 to 110 million years ago. Like most dinosaur genera, ''Acrocanthosaurus'' contains only a single species, ''A. atokensis''. Its fossil remains are found mainly in the U.S. states of Oklahoma, Texas, and Wyoming, although teeth attributed to ''Acrocanthosaurus'' have been found as far east as Maryland, suggesting a continent wide range. ''Acrocanthosaurus'' was a bipedal predator. As the name suggests, it is best known for the high neural spines on many of its vertebrae, which most likely supported a ridge of muscle over the animal's neck, back, and hips. ''Acrocanthosaurus'' was one of the largest theropods, with the largest known specimen reaching in length and weighing approximately . Large theropod footprints discovered in Texas may have been made by ''Acrocanthosaurus'', although ther ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antlers Formation
The Antlers Formation is a stratum which ranges from Arkansas through southern Oklahoma into northeastern Texas. The stratum is thick consisting of silty to sandy mudstone and fine to coarse grained sandstone that is poorly to moderately sorted. The stratum is cemented with clay and calcium carbonate. In places the sandstone may be conglomeratic or ferruginous (rich in iron oxides). Based on correlation with the Trinity Group of Texas, the Antlers Formation is estimated to be late Aptian-early Albian. This age range is supported by the presence of two dinosaurs that are also known from the Cloverly Formation, ''Deinonychus'' and ''Tenontosaurus''. Amphibians Indeterminate frog remains. Possible indeterminate salamander remains. Fish References: Cifelli ''et al.'' 1999; Wedel ''et al.'' 2000, Kielan-Jarorowska and Cifelli 2001; Nydam and Cifelli 2002. Cartilaginous fish Ray-finned fish Possible indeterminate amid remains. Possible indeterminate lepisosteid remains. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carboniferous
The Carboniferous ( ) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago ( Mya), to the beginning of the Permian Period, million years ago. The name ''Carboniferous'' means "coal-bearing", from the Latin '' carbō'' ("coal") and '' ferō'' ("bear, carry"), and refers to the many coal beds formed globally during that time. The first of the modern 'system' names, it was coined by geologists William Conybeare and William Phillips in 1822, based on a study of the British rock succession. The Carboniferous is often treated in North America as two geological periods, the earlier Mississippian and the later Pennsylvanian. Terrestrial animal life was well established by the Carboniferous Period. Tetrapods (four limbed vertebrates), which had originated from lobe-finned fish during the preceding Devonian, became pentadactylous in and diversified during the Carboniferous, including early amphibian line ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unconformity
An unconformity is a buried erosional or non-depositional surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer was exposed to erosion for an interval of time before deposition of the younger layer, but the term is used to describe any break in the sedimentary geologic record. The significance of angular unconformity (see below) was shown by James Hutton, who found examples of Hutton's Unconformity at Jedburgh in 1787 and at Siccar Point in 1788. The rocks above an unconformity are younger than the rocks beneath (unless the sequence has been overturned). An unconformity represents time during which no sediments were preserved in a region or were subsequently eroded before the next deposition. The local record for that time interval is missing and geologists must use other clues to discover that part of the geologic history of that area. The interval of geologic time not represented is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
