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Debeerius
''Debeerius'' is a genus of chondrichthyan from the Mississippian age Bear Gulch Limestone of Montana, United States. It is named after Gavin de Beer Sir Gavin Rylands de Beer (1 November 1899 – 21 June 1972) was a British evolutionary embryologist, known for his work on heterochrony as recorded in his 1930 book ''Embryos and Ancestors''. He was director of the Natural History Museum, Lon .... One species, ''D. ellefseni'', is known. References Prehistoric cartilaginous fish genera Mississippian fish Fossil taxa described in 2000 Mississippian fish of North America {{Paleo-cartilaginous-fish-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bear Gulch Limestone
The Bear Gulch Limestone is a limestone-rich geological lens in central Montana, renowned for the quality of its late Mississippian-aged fossils. It is exposed over a number of outcrops northeast of the Big Snowy Mountains, and is often considered a component of the more widespread Heath Formation. The Bear Gulch Limestone reconstructs a diverse, though isolated, marine ecosystem which developed near the end of the Serpukhovian age. It is a lagerstätte, a particular type of rock unit with exceptional fossil preservation of both articulated skeletons and soft tissues. Bear Gulch fossils include a variety of fish, invertebrates, and algae occupying a number of different habitats within a preserved shallow bay. Fish include a high diversity of unusual chondrichthyans (cartilaginous fish) and one of the oldest known lampreys, along with other vertebrates. Invertebrates include numerous fossils of crustaceans, worms, cephalopods, and sea sponges, which are concentrated in different ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chondrichthyan
Chondrichthyes (; ) is a class that contains the cartilaginous fishes that have skeletons primarily composed of cartilage. They can be contrasted with the Osteichthyes or ''bony fishes'', which have skeletons primarily composed of bone tissue. Chondrichthyes are jawed vertebrates with paired fins, paired nares, scales, and a heart with its chambers in series. Extant chondrichthyes range in size from the 10 cm (3.9 in) finless sleeper ray to the 10 m (32 ft) whale shark. The class is divided into two subclasses: Elasmobranchii (sharks, rays, skates, and sawfish) and Holocephali (chimaeras, sometimes called ghost sharks, which are sometimes separated into their own class). Within the infraphylum Gnathostomata, cartilaginous fishes are distinct from all other jawed vertebrates. Anatomy Skeleton The skeleton is cartilaginous. The notochord is gradually replaced by a vertebral column during development, except in Holocephali, where the notochord stays intact. In some deepwater s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mississippian Age
The Mississippian ( , also known as Lower Carboniferous or Early Carboniferous) is a subperiod in the geologic timescale or a subsystem of the geologic record. It is the earlier of two subperiods of the Carboniferous period lasting from roughly 358.9 to 323.2 million years ago. As with most other geochronologic units, the rock beds that define the Mississippian are well identified, but the exact start and end dates are uncertain by a few million years. The Mississippian is so named because rocks with this age are exposed in the Mississippi Valley. The Mississippian was a period of marine transgression in the Northern Hemisphere: the sea level was so high that only the Fennoscandian Shield and the Laurentian Shield were dry land. The cratons were surrounded by extensive delta systems and lagoons, and carbonate sedimentation on the surrounding continental platforms, covered by shallow seas. In North America, where the interval consists primarily of marine limestones, it i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., federal district, five major unincorporated territories, nine United States Minor Outlying Islands, Minor Outlying Islands, and 326 Indian reservations. The United States is also in Compact of Free Association, free association with three Oceania, Pacific Island Sovereign state, sovereign states: the Federated States of Micronesia, the Marshall Islands, and the Palau, Republic of Palau. It is the world's List of countries and dependencies by area, third-largest country by both land and total area. It shares land borders Canada–United States border, with Canada to its north and Mexico–United States border, with Mexico to its south and has maritime borders with the Bahamas, Cuba, Russia, and other nations. With a population of over 333 million, it is the List of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gavin De Beer
Sir Gavin Rylands de Beer (1 November 1899 – 21 June 1972) was a British evolutionary embryologist, known for his work on heterochrony as recorded in his 1930 book ''Embryos and Ancestors''. He was director of the Natural History Museum, London, president of the Linnean Society of London, and a winner of the Royal Society's Darwin Medal for his studies on evolution. Biography Born on 1 November 1899 in Malden, Surrey (now part of London), de Beer spent most of his childhood in France, where he was educated at the Parisian École Pascal. During this time, he also visited Switzerland, a country with which he remained fascinated for the rest of his life. His education continued at Harrow and Magdalen College, Oxford, where he graduated with a degree in zoology in 1921, after a pause to serve in the First World War in the Grenadier Guards and the Army Education Corps. In 1923 he was made a fellow of Merton College, Oxford, and began to teach at the university's zoology depar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Journal Of Morphology
The ''Journal of Morphology'' is a peer-reviewed scientific journal In academic publishing, a scientific journal is a periodical publication intended to further the progress of science, usually by reporting new research. Content Articles in scientific journals are mostly written by active scientists such as s ... of anatomy and morphology featuring primary research articles, review articles, and meeting abstracts. The journal was established in 1887 by zoologists and morphologists Edward Phelps Allis and C. O. Whitman. The journal appeared regularly from 1887 onwards and made a financial loss. Allis provided the support necessary for the journal to continue appearing until, after a short gap, the journal underwent reorganization in 1907 when it was taken over by Wistar Institute in Philadelphia, as a more permanent solution to its financial problems. As of 2022, it is edited by J. Matthias Starck.''Am. Zool. (1979) 19 (4): 1251-1253.'' According to the '' Journal Cita ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prehistoric Cartilaginous Fish Genera
Prehistory, also known as pre-literary history, is the period of human history between the use of the first stone tools by hominins 3.3 million years ago and the beginning of recorded history with the invention of writing systems. The use of symbols, marks, and images appears very early among humans, but the earliest known writing systems appeared 5000 years ago. It took thousands of years for writing systems to be widely adopted, with writing spreading to almost all cultures by the 19th century. The end of prehistory therefore came at very different times in different places, and the term is less often used in discussing societies where prehistory ended relatively recently. In the early Bronze Age, Sumer in Mesopotamia, the Indus Valley Civilisation, and ancient Egypt were the first civilizations to develop their own scripts and to keep historical records, with their neighbors following. Most other civilizations reached the end of prehistory during the following Iro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mississippian Fish
{{Disambiguation ...
Mississippian may refer to: *Mississippian (geology), a subperiod of the Carboniferous period in the geologic timescale, roughly 360 to 325 million years ago *Mississippian culture, a culture of Native American mound-builders from 900 to 1500 AD *Mississippian Railway, a short line railroad *A native of Mississippi See also *Mississippi (other) Mississippi is a state of the United States of America. Mississippi may also refer to: Places * Mississippi River, a river in central United States * Mississippi River System, a system of rivers in the Mississippi River watershed * Mississippi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fossil Taxa Described In 2000
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in amber, hair, petrified wood and DNA remnants. The totality of fossils is known as the ''fossil record''. Paleontology is the study of fossils: their age, method of formation, and evolutionary significance. Specimens are usually considered to be fossils if they are over 10,000 years old. The oldest fossils are around 3.48 billion years old to 4.1 billion years old. Early edition, published online before print. The observation in the 19th century that certain fossils were associated with certain rock strata led to the recognition of a geological timescale and the relative ages of different fossils. The development of radiometric dating techniques in the early 20th century allowed scientists to quantitatively measure the absolute ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
