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Elmisauridae
Caenagnathidae is a family of bird-like maniraptoran theropod dinosaurs from the Cretaceous of North America and Asia. They are a member of the Oviraptorosauria, and close relatives of the Oviraptoridae. Like other oviraptorosaurs, caenagnathids had specialized beaks, long necks, and short tails, and would have been covered in feathers. The relationships of caenagnathids were long a puzzle. The family was originally named by Raymond Martin Sternberg in 1940 as a family of flightless birds. The discovery of skeletons of the related oviraptorids revealed that they were in fact non-avian theropods, and the discovery of more complete caenagnathid remains revealed that ''Chirostenotes pergracilis'', originally named on the basis of a pair of hands, and ''Citipes elegans'', originally thought to be an ornithomimid, named from a foot, were caenagnathids as well. Anatomy Overall, the anatomy of the caenagnathids is similar to that of the closely related Oviraptoridae, but there ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oviraptoridae
Oviraptoridae is a group of bird-like, herbivorous and omnivorous maniraptoran dinosaurs. Oviraptorids are characterized by their toothless, parrot-like beaks and, in some cases, elaborate crests. They were generally small, measuring between one and two metres long in most cases, though some possible oviraptorids were enormous. Oviraptorids are currently known only from the Late Cretaceous of Asia, with the most well-known species and complete specimens found only in the Gobi Desert of Mongolia and northwestern China. Description The most characteristic feature of this group is the skull structure. Oviraptorids had short snouts and very deep mandibles. Some taxa (such as ''Citipati'', ''Corythoraptor'', ''Rinchenia'') had a midline crest on top of the skull, resembling that of a cassowary. Other distinguishing characteristics include a bony spike intruding on the mandibular fenestra, nostrils placed very high and far back on the snout, an extremely thin bony bar beneath the eye, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oviraptorid Clean
Oviraptoridae is a group of bird-like, herbivorous and omnivorous maniraptoran dinosaurs. Oviraptorids are characterized by their toothless, parrot-like beaks and, in some cases, elaborate crests. They were generally small, measuring between one and two metres long in most cases, though some possible oviraptorids were enormous. Oviraptorids are currently known only from the Late Cretaceous of Asia, with the most well-known species and complete specimens found only in the Gobi Desert of Mongolia and northwestern China. Description The most characteristic feature of this group is the skull structure. Oviraptorids had short snouts and very deep mandibles. Some taxa (such as ''Citipati'', ''Corythoraptor'', ''Rinchenia'') had a midline crest on top of the skull, resembling that of a cassowary. Other distinguishing characteristics include a bony spike intruding on the mandibular fenestra, nostrils placed very high and far back on the snout, an extremely thin bony bar beneath the eye, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Halszka Osmólska
Halszka Osmólska (September 15, 1930 – March 31, 2008) was a Polish paleontologist who had specialized in Mongolian dinosaurs. Biography She was born in 1930 in Poznań. In 1949, she began to study biology at Faculty of Biology and Earth Sciences of the University of Poznań before moving to Warsaw and studying at the Warsaw University, which she graduated from in 1955. Since then she worked at the Institute of Paleobiology of the Polish Academy of Sciences (PAN). Between 1983–1988, she served as the institute's director. She was a member of the Polish–Mongolian expeditions to the Gobi Desert (1963–1965 and 1967–1971) and she described many finds from these rocks, often with Teresa Maryańska. Among the dinosaurs she described are: * ''Elmisaurus'' (and Elmisauridae) (1981), ''Hulsanpes'' (1982), '' Borogovia'' (1987), and ''Bagaraatan'' (1996) * with Maryańska, ''Homalocephale'', ''Prenocephale'', and ''Tylocephale'' (and Pachycephalosauria)(1974), ''Bagaceratops'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Early Cretaceous
The Early Cretaceous ( geochronological name) or the Lower Cretaceous (chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145 Ma to 100.5 Ma. Geology Proposals for the exact age of the Barremian-Aptian boundary ranged from 126 to 117 Ma until recently (as of 2019), but based on drillholes in Svalbard the defining early Aptian Oceanic Anoxic Event 1a (OAE1a) was carbon isotope dated to 123.1±0.3 Ma, limiting the possible range for the boundary to c. 122–121 Ma. There is a possible link between this anoxic event and a series of Early Cretaceous large igneous provinces (LIP). The Ontong Java-Manihiki-Hikurangi large igneous province, emplaced in the South Pacific at c. 120 Ma, is by far the largest LIP in Earth's history. The Ontong Java Plateau today covers an area of 1,860,000 km2. In the Indian Ocean another LIP began to form at c. 120 Ma, the Kerguelen P ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caenagnathus
''Caenagnathus'' ('recent jaw') is a genus of caenagnathid oviraptorosaurian dinosaur from the late Cretaceous period (Campanian stage; ~75 million years ago). It is known from partial remains including lower jaws, a tail vertebra, hand bones, and hind limbs, all found in the Dinosaur Park Formation of Alberta, Canada. ''Caenagnathus'' measured about long and weighed about . Description ''Caenagnathus'' was a large oviraptorosaurian, with some specimens suggesting it achieved sizes comparable to its relative ''Anzu''. Like ''Anzu'', it had a toothless lower beak that was shallower in depth than those of elmisaurines. It also shared with ''Anzu'' less gracile proportions than those of elmisaurines. Like all oviraptorosaurs, it would most likely have possessed a coat of feathers. Classification This dinosaur has a confusing history. In 1936, a set of jaws (CMN 8776) were found, and later given the name ''Caenagnathus'', meaning 'recent jaw'; they were first thought to be tho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Convergent Evolution
Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last common ancestor of those groups. The cladistic term for the same phenomenon is homoplasy. The recurrent evolution of flight is a classic example, as flying insects, birds, pterosaurs, and bats have independently evolved the useful capacity of flight. Functionally similar features that have arisen through convergent evolution are ''analogous'', whereas '' homologous'' structures or traits have a common origin but can have dissimilar functions. Bird, bat, and pterosaur wings are analogous structures, but their forelimbs are homologous, sharing an ancestral state despite serving different functions. The opposite of convergence is divergent evolution, where related species evolve different traits. Convergent evolution is similar to parallel evo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ostrich
Ostriches are large flightless birds of the genus ''Struthio'' in the order Struthioniformes, part of the infra-class Palaeognathae, a diverse group of flightless birds also known as ratites that includes the emus, rheas, and kiwis. There are two living species of ostrich: the common ostrich, native to large areas of sub-Saharan Africa and the Somali ostrich, native to the Horn of Africa. The common ostrich was also historically native to the Arabian Peninsula, and ostriches were present across Asia as far east as Mongolia during the Late Pleistocene and possibly into the Holocene. They lay the largest eggs of any living land animal. With the ability to run at 70 km/h (43.5 mph), they are the fastest birds on land. They are farmed worldwide, particularly for their feathers as they are used as decoration and feather dusters. Their skin is also used for leather products. They are the heaviest living birds. Taxonomic history The genus ''Struthio'' was first described b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paleognathae
Palaeognathae (; ) is a infraclass of birds, called paleognaths, within the class Aves of the clade Archosauria. It is one of the two extant infraclasses of birds, the other being Neognathae, both of which form Neornithes. Palaeognathae contains five extant branches of flightless lineages (plus two extinct clades), termed ratites, and one flying lineage, the Neotropic tinamous.Wetmore, A. (1960) A Classification for Birds of the World. Smithsonian Miscellaneous Collection (Washington D.C.: Smithsonian Institution) 139: 1–37. There are 47 species of tinamous, five of kiwis (''Apteryx''), three of cassowaries (''Casuarius''), one of emus (''Dromaius'') (another became extinct in historic times), two of rheas (''Rhea'') and two of ostrich (''Struthio'').Clements, J. C. ''et al''. (2010) Recent research has indicated that paleognaths are monophyletic but the traditional taxonomic split between flightless and flighted forms is incorrect; tinamous are within the ratite radiation, me ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oviraptorosauria
Oviraptorosaurs ("egg thief lizards") are a group of feathered maniraptoran dinosaurs from the Cretaceous Period of what are now Asia and North America. They are distinct for their characteristically short, beaked, parrot-like skulls, with or without bony crests atop the head. They ranged in size from ''Caudipteryx'', which was the size of a turkey, to the 8-meter-long, 1.4-ton ''Gigantoraptor''. The group (along with all maniraptoran dinosaurs) is close to the ancestry of birds. Some researchers such as Maryanska ''et al'' (2002) and Osmólska ''et al.'' (2004) have proposed that they may represent primitive flightless birds.Osmólska, Halszka, Currie, Philip J., Brasbold, Rinchen (2004) "The Dinosauria" Weishampel, Dodson, Osmólska. "Chapter 8 Oviraptorosauria" University of California Press. The most complete oviraptorosaur specimens have been found in Asia. The North American oviraptorosaur record is sparse.Varricchio, D. J. 2001. Late Cretaceous oviraptorosaur (Theropoda) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dinosaur
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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theropod
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 231.4 million years ago ( 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 diets was historically considered a characteri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maniraptora
Maniraptora is a clade of coelurosaurian dinosaurs which includes the birds and the non-avian dinosaurs that were more closely related to them than to ''Ornithomimus velox''. It contains the major subgroups Avialae, Deinonychosauria, Oviraptorosauria and Therizinosauria. '' Ornitholestes'' and the Alvarezsauroidea are also often included. Together with the next closest sister group, the Ornithomimosauria, Maniraptora comprises the more inclusive clade Maniraptoriformes. Maniraptorans first appear in the fossil record during the Jurassic Period (see '' Eshanosaurus''), and survive today as living birds. Description Maniraptorans are characterized by long arms and three-fingered hands (though reduced or fused in some lineages), as well as a "half-moon shaped" (semi-lunate) bone in the wrist (carpus). In 2004, Tom Holtz and Halszka Osmólska pointed out six other maniraptoran characters relating to specific details of the skeleton. Unlike most other saurischian dinosaurs, which h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
