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Aublysodon
''Aublysodon'' (“backwards-flowing tooth") is a genus of carnivorous dinosaurs known only from the Judith River Formation in Montana, which has been dated to the late Campanian age of the late Cretaceous period (about 75 million years ago). The only currently recognized species, ''Aublysodon mirandus'', was named by paleontologist Joseph Leidy in 1868. It is now considered dubious, because the type specimen consists only of an isolated premaxillary (front) tooth. Although this specimen is now lost, similar teeth have been found in many US states, western Canada, and Asia. These teeth almost certainly belong to juvenile tyrannosaurine tyrannosaurids, but most have not been identified to species level. However, it is likely that the type tooth (and therefore the name ''Aublysodon mirandus'' itself) belongs to one of the species in the genus ''Daspletosaurus'', which was present in contemporary formations, and which matches specific details of the original tooth. The synapomorphies ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tyrannosauridae
Tyrannosauridae (or tyrannosaurids, meaning "tyrant lizards") is a family of coelurosaurian theropod dinosaurs that comprises two subfamilies containing up to thirteen genera, including the eponymous ''Tyrannosaurus''. The exact number of genera is controversial, with some experts recognizing as few as three. All of these animals lived near the end of the Cretaceous Period and their fossils have been found only in North America and Asia. Although descended from smaller ancestors, tyrannosaurids were almost always the largest predators in their respective ecosystems, putting them at the apex of the food chain. The largest species was ''Tyrannosaurus rex'', one of the largest and most massive known land predators, which measured over in length and according to most modern estimates to in weight. Tyrannosaurids were bipedal carnivores with massive skulls filled with large teeth. Despite their large size, their legs were long and proportioned for fast movement. In contrast, their ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Daspletosaurus
''Daspletosaurus'' ( ; meaning "frightful lizard") is a genus of tyrannosaurid dinosaur that lived in Laramidia between about 79.5 and 74 million years ago, during the Late Cretaceous Period. The genus ''Daspletosaurus'' contains three species. Fossils of the earlier type species, ''D. torosus'', have been found in Alberta, and fossils of a later second species, ''D. wilsoni,'' and third species, ''D. horneri'', have been found only in Montana. A possible fourth species, also from Alberta, awaits formal identification. The taxon ''Thanatotheristes'' has been suggested to represent a species of ''Daspletosaurus'', ''D. degrootorum'', but this has not been widely supported. ''Daspletosaurus'' is closely related to the much larger and more recent tyrannosaurid ''Tyrannosaurus rex''. Like most tyrannosaurids, ''Daspletosaurus'' was a multi-tonne bipedal predator equipped with dozens of large, sharp teeth. ''Daspletosaurus'' had the small forelimbs typical of tyrannosaurids, although ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ornithomimus
''Ornithomimus'' (; "bird mimic") is a genus of ornithomimid dinosaurs from the Late Cretaceous Period of what is now North America. ''Ornithomimus'' was a swift bipedal theropod which fossil evidence indicates was covered in feathers, equipped with a small toothless beak that may indicate an omnivorous diet. It is usually classified into two species: the type species, ''Ornithomimus velox'', and a referred species, ''Ornithomimus edmontonicus''. ''O. velox'' was named in 1890 by Othniel Charles Marsh on the basis of a foot and partial hand from the late Maastrichtian-age Denver Formation of Colorado, United States. Another seventeen species have been named since, though most of them have subsequently been assigned to new genera or shown to be not directly related to ''Ornithomimus velox''. The best material of species still considered part of the genus has been found in Alberta, Canada, representing the species ''O. edmontonicus'', known from several skeletons from the early Maast ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Judith River Formation
The Judith River Formation is a fossil-bearing geologic formation in Montana, and is part of the Judith River Group. It dates to the Late Cretaceous, between 79 and 75.3 million years ago, corresponding to the "Judithian" land vertebrate age. It was laid down during the same time period as portions of the Two Medicine Formation of MontanaSullivan, R.M. and Lucas, S. G. (2006). "The Kirtlandian land-vertebrate "age"–faunal composition, temporal position and biostratigraphic correlation in the nonmarine Upper Cretaceous of western North America." Pp. 7-29 in Lucas, S. G. and Sullivan, R.M. (eds.), ''Late Cretaceous vertebrates from the Western Interior. New Mexico Museum of Natural History and Science Bulletin 35''. and the Oldman Formation of Alberta. It is an historically important formation, explored by early American paleontologists such as Edward Drinker Cope, who named several dinosaurs from scrappy remains found here on his 1876 expedition (such as ''Monoclonius''). Modern ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Troodon
''Troodon'' ( ; ''Troödon'' in older sources) is a wastebasket taxon and a dubious genus of relatively small, bird-like dinosaurs known definitively from the Campanian age of the Late Cretaceous period (about 77 mya). It includes at least one species, ''Troodon formosus'', known from Montana. Discovered in October 1855, ''T. formosus'' was among the first dinosaurs found in North America, although it was thought to be a lizard until 1877. Several well-known troodontid specimens from the Dinosaur Park Formation in Alberta were once believed to be members of this genus. However, recent analyses in 2017 have found the genus to be undiagnostic and referred some of these specimens to the genus ''Stenonychosaurus'' (long believed to be synonymous with ''Troodon'') and others to the genus ''Latenivenatrix''. The genus name is Ancient Greek for "wounding tooth", referring to the teeth, which were different from those of most other theropods known at the time of their discovery. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Palaeoscincus
''Palaeoscincus'' (meaning "ancient skink" from the Greek παλαιός and σκίγγος) is a dubious genus of ankylosaurian dinosaur based on teeth from the mid-late Campanian-age Upper Cretaceous Judith River Formation of Montana. Like several other dinosaur genera named by Joseph Leidy (''Deinodon'', '' Thespesius'', and ''Trachodon''), it is an historically important genus with a convoluted taxonomy that has been all but abandoned by modern dinosaur paleontologists. Because of its wide use in the early 20th century, it was somewhat well known to the general public, often through illustrations of an animal with the armor of ''Edmontonia'' and the tail club of an ankylosaurid. Reassigned species Seven species have been referred to this genus over the years, six of which have since been reassigned to other genera: *''Palaeoscincus africanus'', named by Robert Broom in 1910/1912, a partial jaw from the Tithonian-Valanginian-age Upper Jurassic-Lower Cretaceous Kirkwood Form ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trachodon
''Trachodon'' (meaning "rough tooth") is a dubious genus of hadrosaurid dinosaur based on teeth from the Campanian-age Upper Cretaceous Judith River Formation of Montana, U.S.Leidy, J. (1856). "Notice of remains of extinct reptiles and fishes, discovered by F. V. Hayden in the Bad Lands of the Judith River, Nebraska Territories." ''Proceedings of the Academy of Natural Science Philadelphia'', 8(25 March): 72–73. It is a historically important genus with a convoluted taxonomy that has been all but abandoned by modern dinosaur paleontologists.Creisler, B.S. (2007). Deciphering duckbills. in: K. Carpenter (ed.), ''Horns and Beaks: Ceratopsian and Ornithopod Dinosaurs''. Indiana University Press: Bloomington and Indianapolis, 185–210. Despite being used for decades as the iconic duckbill dinosaur, the material it is based on is composed of teeth from both duckbills and ceratopsids (their teeth have a distinctive double rootHatcher, J.B., Marsh, O.C. and Lull, R.S. (1907). ''Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Taxonomy (biology)
In biology, taxonomy () is the scientific study of naming, defining ( circumscribing) and classifying groups of biological organisms based on shared characteristics. Organisms are grouped into taxa (singular: taxon) and these groups are given a taxonomic rank; groups of a given rank can be aggregated to form a more inclusive group of higher rank, thus creating a taxonomic hierarchy. The principal ranks in modern use are domain, kingdom, phylum (''division'' is sometimes used in botany in place of ''phylum''), class, order, family, genus, and species. The Swedish botanist Carl Linnaeus is regarded as the founder of the current system of taxonomy, as he developed a ranked system known as Linnaean taxonomy for categorizing organisms and binomial nomenclature for naming organisms. With advances in the theory, data and analytical technology of biological systematics, the Linnaean system has transformed into a system of modern biological classification intended to reflect the evolu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Badlands
Badlands are a type of dry terrain where softer sedimentary rocks and clay-rich soils have been extensively eroded."Badlands" in ''Chambers's Encyclopædia''. London: George Newnes, 1961, Vol. 2, p. 47. They are characterized by steep slopes, minimal vegetation, lack of a substantial regolith, and high drainage density.A.J. Parsons and A.D. Abrahams, Editors (2009) ''Geomorphology of Desert Environments'' (2nd ed.) Springer Science & Business Media Ravines, gullies, buttes, hoodoos and other such geologic forms are common in badlands. Badlands are found on every continent except Antarctica, being most common where there are unconsolidated sediments. They are often difficult to navigate by foot, and are unsuitable for agriculture. Most are a result of natural processes, but destruction of vegetation by overgrazing or pollution can produce anthropogenic badlands. Badlands topography Badlands are characterized by a distinctive badlands topography. This is terrain in which w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Type Species
In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen(s). Article 67.1 A similar concept is used for suprageneric groups and called a type genus. In botanical nomenclature, these terms have no formal standing under the code of nomenclature, but are sometimes borrowed from zoological nomenclature. In botany, the type of a genus name is a specimen (or, rarely, an illustration) which is also the type of a species name. The species name that has that type can also be referred to as the type of the genus name. Names of genus and family ranks, the various subdivisions of those ranks, and some higher-rank names based on genus names, have such types. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sexual Morph
Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different Morphology (biology), morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most animals and some plants. Differences may include secondary sex characteristics, size, weight, colour, markings, or behavioural or cognitive traits. These differences may be subtle or exaggerated and may be subjected to sexual selection and natural selection. The opposite of dimorphism is ''monomorphism'', which is when both biological sexes are phenotype, phenotypically indistinguishable from each other. Overview Ornamentation and coloration Common and easily identified types of dimorphism consist of Biological ornament, ornamentation and coloration, though not always apparent. A difference in coloration of sexes within a given species is called sexual dichromatism, which is commonly seen in many species of birds and rep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ontogenetic
Ontogeny (also ontogenesis) is the origination and development of an organism (both physical and psychological, e.g., moral development), usually from the time of fertilization of the egg to adult. The term can also be used to refer to the study of the entirety of an organism's lifespan. Ontogeny is the developmental history of an organism within its own lifetime, as distinct from phylogeny, which refers to the evolutionary history of a species. Another way to think of ontogeny is that it is the process of an organism going through all of the developmental stages over its lifetime. The developmental history includes all the developmental events that occur during the existence of an organism, beginning with the changes in the egg at the time of fertilization and events from the time of birth or hatching and afterward (i.e., growth, remolding of body shape, development of secondary sexual characteristics, etc.). While developmental (i.e., ontogenetic) processes can influence su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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