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Priconodon
''Priconodon'' (meaning "saw cone tooth") is an extinct genus of dinosaur (perhaps nodosaurid), known from its large teeth. Its remains have been found in the Aptian-Albian age Lower Cretaceous Arundel Formation of Muirkirk, Prince George's County, Maryland, USA and the Potomac Group, also located in Maryland. History O. C. Marsh named the genus for USNM 2135, a large worn tooth from what was then called the Potomac Formation. As ankylosaurians were by and large unknown at the time, he compared it to '' Diracodon'' (=''Stegosaurus'') teeth.Marsh, O.C. (1888). Notice of a new genus of Sauropoda and other new dinosaurs from the Potomac Formation. ''American Journal of Science'' 135:89-94. It was not identified as an ankylosaurian until Walter Coombs assigned it to Nodosauridae in 1978.Coombs, Jr., W.P. (1978). The families of the ornithischian dinosaur order Ankylosauria. ''Palaeontology'' 21(1):143-170. In 1998 Kenneth Carpenter and James Kirkland, in a review of North American ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Priconodon 1
''Priconodon'' (meaning "saw cone tooth") is an extinct genus of dinosaur (perhaps nodosaurid), known from its large teeth. Its remains have been found in the Aptian-Albian age Lower Cretaceous Arundel Formation of Muirkirk, Prince George's County, Maryland, USA and the Potomac Group, also located in Maryland. History O. C. Marsh named the genus for USNM 2135, a large worn tooth from what was then called the Potomac Formation. As ankylosaurians were by and large unknown at the time, he compared it to '' Diracodon'' (=''Stegosaurus'') teeth.Marsh, O.C. (1888). Notice of a new genus of Sauropoda and other new dinosaurs from the Potomac Formation. ''American Journal of Science'' 135:89-94. It was not identified as an ankylosaurian until Walter Coombs assigned it to Nodosauridae in 1978.Coombs, Jr., W.P. (1978). The families of the ornithischian dinosaur order Ankylosauria. ''Palaeontology'' 21(1):143-170. In 1998 Kenneth Carpenter and James Kirkland, in a review of North American ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nodosaurid
Nodosauridae is a family of ankylosaurian dinosaurs, from the Late Jurassic to the Late Cretaceous period in what is now North America, South America, Europe, and Asia. Description Nodosaurids, like their close relatives the ankylosaurids, were heavily armored dinosaurs adorned with rows of bony armor nodules and spines (osteoderms), which were covered in keratin sheaths. All nodosaurids, like other ankylosaurians, were medium-sized to large, heavily built, quadrupedal, herbivorous dinosaurs, possessing small, leaf-shaped teeth. Unlike ankylosaurids, nodosaurids lacked mace-like tail clubs, instead having flexible tail tips. Many nodosaurids had spikes projecting outward from their shoulders. One particularly well-preserved nodosaurid "mummy", known as the Suncor nodosaur (''Borealopelta markmitchelli''), preserved a nearly complete set of armor in life position, as well as the keratin covering and mineralized remains of the underlying skin, which indicate reddish dorsal pigmen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nodosauridae
Nodosauridae is a family of ankylosaurian dinosaurs, from the Late Jurassic to the Late Cretaceous period in what is now North America, South America, Europe, and Asia. Description Nodosaurids, like their close relatives the ankylosaurids, were heavily armored dinosaurs adorned with rows of bony armor nodules and spines (osteoderms), which were covered in keratin sheaths. All nodosaurids, like other ankylosaurians, were medium-sized to large, heavily built, quadrupedal, herbivorous dinosaurs, possessing small, leaf-shaped teeth. Unlike ankylosaurids, nodosaurids lacked mace-like tail clubs, instead having flexible tail tips. Many nodosaurids had spikes projecting outward from their shoulders. One particularly well-preserved nodosaurid "mummy", known as the Suncor nodosaur (''Borealopelta markmitchelli''), preserved a nearly complete set of armor in life position, as well as the keratin covering and mineralized remains of the underlying skin, which indicate reddish dorsal pigmen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arundel Formation
The Arundel Formation, also known as the Arundel Clay, is a clay-rich sedimentary rock formation, within the Potomac Group, found in Maryland of the United States of America. It is of Aptian age (Lower Cretaceous). This rock unit had been economically important as a source of iron ore, but is now more notable for its dinosaur fossils. It consists of clay lenses within depressions in the upper part of the Patuxent Formation that may represent oxbow swamp facies. It is named for Anne Arundel County, Maryland. Vertebrate paleofauna Dinosaurs Dinosaurs present include cf. ''Acrocanthosaurus'', the possible ornithischian ''Magulodon'', the poorly known theropods ''"Allosaurus" medius'', '' "Creosaurus" potens'', and ''"Coelurus" gracilis'', the ornithomimosaurian ''"Dryosaurus" grandis'', as well as another indeterminate ornithomimosaurian (though it most likely is ''Nedcolbertia''), the sauropod ''Astrodon'', the nodosaurid ''Priconodon'', a possible basal ceratopsian, and potential ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Othniel Charles Marsh
Othniel Charles Marsh (October 29, 1831 – March 18, 1899) was an American professor of Paleontology in Yale College and President of the National Academy of Sciences. He was one of the preeminent scientists in the field of paleontology. Among his legacies are the discovery or description of dozens of new species and theories on the origins of birds. Born into a modest family, Marsh was able to afford higher education thanks to the generosity of his wealthy uncle George Peabody. After graduating from Yale College in 1860 he travelled the world, studying anatomy, mineralogy and geology. He obtained a teaching position at Yale upon his return. From the 1870s to 1890s, he competed with rival paleontologist Edward Drinker Cope in a period of frenzied Western American expeditions known as the Bone Wars. Marsh's greatest legacy is the collection of Mesozoic reptiles, Cretaceous birds, and Mesozoic and Tertiary mammals that now constitute the backbone of the collections of Yale's Peabo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Potomac Formation
The Potomac Group is a geologic group in Delaware, Maryland, New Jersey, and Virginia. It preserves fossils dating back to the Cretaceous period. An indeterminate tyrannosauroid and '' Priconodon crassus'', a nodosaurid, are known from indeterminate sediments belonging to the Potomac Group. The Potomac Group was initially believed to have been Late Jurassic in age by Othniel Charles MarshMarsh, O.C. (1888). Notice of a new genus of Sauropoda and other new dinosaurs from the Potomac Formation. ''American Journal of Science'' 135:89-94. but later studies, such as Clark (1897), have found that the Potomac Group is in fact Early-Late Cretaceous (Aptian-Turonian) in age.Clark, W.B., (1897), Outline of present knowledge of the physical features of Maryland: Maryland Geological Survey Volume Series, v. 1, pt. 3, p. 172-188. See also * List of fossiliferous stratigraphic units in Virginia * Paleontology in Virginia Paleontology in Virginia refers to paleontological research occurring ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Potomac Group
The Potomac Group is a geologic group in Delaware, Maryland, New Jersey, and Virginia. It preserves fossils dating back to the Cretaceous period. An indeterminate tyrannosauroid and '' Priconodon crassus'', a nodosaurid, are known from indeterminate sediments belonging to the Potomac Group. The Potomac Group was initially believed to have been Late Jurassic in age by Othniel Charles MarshMarsh, O.C. (1888). Notice of a new genus of Sauropoda and other new dinosaurs from the Potomac Formation. ''American Journal of Science'' 135:89-94. but later studies, such as Clark (1897), have found that the Potomac Group is in fact Early-Late Cretaceous (Aptian-Turonian) in age.Clark, W.B., (1897), Outline of present knowledge of the physical features of Maryland: Maryland Geological Survey Volume Series, v. 1, pt. 3, p. 172-188. See also * List of fossiliferous stratigraphic units in Virginia * Paleontology in Virginia Paleontology in Virginia refers to paleontological research occurring w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prince George's County, Maryland
) , demonym = Prince Georgian , ZIP codes = 20607–20774 , area codes = 240, 301 , founded date = April 23 , founded year = 1696 , named for = Prince George of Denmark , leader_title = Executive , leader_name = Angela D. Alsobrooks ( D) , seat wl = Upper Marlboro , largest city wl = Bowie , area_total_sq_mi = 499 , area_land_sq_mi = 483 , area_water_sq_mi = 16 , area percentage = 3.2 , census yr = 2020 , pop = 967201 , pop_est_as_of = 2021 , population_est = , density_sq_mi = 1900 , district = 4th , district2 = 5th , time zone = Eastern , web = www.princegeorgescountymd.gov Prince George's County (often shortened to PG County) is a county located in the U.S. state of Maryland bordering the eastern portion of Washington, D.C. As of the 2020 U.S. census, the population was 967,201, making it the second-most populous county in Maryland, behind Montgomery County. The 2020 census counted an increase of nearly 104,000 in the previous ten years. Its c ... [...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] |
James Kirkland (paleontologist)
James Ian Kirkland (born August 24, 1954) is an American paleontologist and geologist. He has worked with dinosaur remains from the south west United States of America and Mexico and has been responsible for discovering new and important genera. He named (or worked with others in naming) ''Animantarx'', '' Cedarpelta'', '' Eohadrosaurus'' ('' nomen nudum'', now named ''Eolambia''), '' Jeyawati'', '' Gastonia'', ''Mymoorapelta'', '' Nedcolbertia'', ''Utahraptor'', ''Zuniceratops'', ''Europelta'' and ''Diabloceratops''. At the same site where he found '' Gastonia'' and ''Utahraptor'', Kirkland has also excavated fossils of the therizinosaur ''Falcarius''.Kirkland, Zanno, Sampson, Clark & DeBlieux 2005, pp. 84-87. Career Born August 24, 1954, Weymouth, Massachusetts. High School, Marshfield High School, Marshfield, Massachusetts. 1972 B.S. Geological Sciences, New Mexico Institute of Mining and Technology, Socorro, New Mexico. 1977 (Pres. Student Body, 1975-1976) M.S. Geology, Nor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cladistics
Cladistics (; ) is an approach to biological classification in which organisms are categorized in groups (" clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is typically shared derived characteristics ( synapomorphies'')'' that are not present in more distant groups and ancestors. However, from an empirical perspective, common ancestors are inferences based on a cladistic hypothesis of relationships of taxa whose character states can be observed. Theoretically, a last common ancestor and all its descendants constitute a (minimal) clade. Importantly, all descendants stay in their overarching ancestral clade. For example, if the terms ''worms'' or ''fishes'' were used within a ''strict'' cladistic framework, these terms would include humans. Many of these terms are normally used paraphyletically, outside of cladistics, e.g. as a 'grade', which are fruitless to precisely delineate, especially when including extinct species. R ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
North America
North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Caribbean Sea, and to the west and south by the Pacific Ocean. Because it is on the North American Plate, North American Tectonic Plate, Greenland is included as a part of North America geographically. North America covers an area of about , about 16.5% of Earth's land area and about 4.8% of its total surface. North America is the third-largest continent by area, following Asia and Africa, and the list of continents and continental subregions by population, fourth by population after Asia, Africa, and Europe. In 2013, its population was estimated at nearly 579 million people in List of sovereign states and dependent territories in North America, 23 independent states, or about 7.5% of the world's population. In Americas (terminology)#Human ge ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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