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Cope-Depéret Rule
Cope's rule, named after American paleontologist Edward Drinker Cope, postulates that population lineages tend to increase in body size over evolutionary time. It was never actually stated by Cope, although he favoured the occurrence of linear evolutionary trends. It is sometimes also known as the Cope–Depéret rule, because Charles Depéret explicitly advocated the idea. Theodor Eimer had also done so earlier. The term "Cope's rule" was apparently coined by Bernhard Rensch, based on the fact that Depéret had "lionized Cope" in his book. While the rule has been demonstrated in many instances, it does not hold true at all taxonomic levels, or in all clades. Larger body size is associated with increased fitness for a number of reasons, although there are also some disadvantages both on an individual and on a clade level: clades comprising larger individuals are more prone to extinction, which may act to limit the maximum size of organisms. Function Effects of growth Directiona ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Juramaia
''Juramaia'' is an extinct genus of very basal eutherian mammal known from the Late Jurassic ( Oxfordian stage) deposits of western Liaoning, China. It is a small shrew-like mammal with a body length of approximately 70–100 mm, making it similar in size to the modern De Winton's shrew. ''Juramaia'' is known from the holotype BMNH PM1343, an articulated and nearly complete skeleton including incomplete skull preserved with full dentition. Discovery It was collected in the Daxigou site, Jianchang, from the Tiaojishan Formation dated at about . It was first named by Zhe-Xi Luo, Chong-Xi Yuan, Qing-Jin Meng and Qiang Ji in 2011 and the type species is ''Juramaia sinensis''. Evolution The discovery of ''Juramaia'' provides new insight into the evolution of placental mammals by showing that their lineage diverged from that of the marsupials 35 million years earlier than previously thought. Furthermore, its discovery fills gaps in the fossil record and helps to calibrate mod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organisms
In biology, an organism () is any living system that functions as an individual entity. All organisms are composed of cells (cell theory). Organisms are classified by taxonomy into groups such as multicellular animals, plants, and fungi; or unicellular microorganisms such as protists, bacteria, and archaea. All types of organisms are capable of reproduction, growth and development, maintenance, and some degree of response to stimuli. Beetles, squids, tetrapods, mushrooms, and vascular plants are examples of multicellular organisms that differentiate specialized tissues and organs during development. A unicellular organism may be either a prokaryote or a eukaryote. Prokaryotes are represented by two separate domains – bacteria and archaea. Eukaryotic organisms are characterized by the presence of a membrane-bound cell nucleus and contain additional membrane-bound compartments called organelles (such as mitochondria in animals and plants and plastids in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Palaeobiologist
Paleobiology (or palaeobiology) is an interdisciplinary field that combines the methods and findings found in both the earth sciences and the life sciences. Paleobiology is not to be confused with geobiology, which focuses more on the interactions between the biosphere and the physical Earth. Paleobiological research uses biological field research of current biota and of fossils millions of years old to answer questions about the molecular evolution and the evolutionary history of life. In this scientific quest, macrofossils, microfossils and trace fossils are typically analyzed. However, the 21st-century biochemical analysis of DNA and RNA samples offers much promise, as does the biometric construction of phylogenetic trees. An investigator in this field is known as a paleobiologist. Important research areas *Paleobotany applies the principles and methods of paleobiology to flora, especially green land plants, but also including the fungi and seaweeds (algae). See also myc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sensu
''Sensu'' is a Latin word meaning "in the sense of". It is used in a number of fields including biology, geology, linguistics, semiotics, and law. Commonly it refers to how strictly or loosely an expression is used in describing any particular concept, but it also appears in expressions that indicate the convention or context of the usage. Common qualifiers ''Sensu'' is the ablative case of the noun ''sensus'', here meaning "sense". It is often accompanied by an adjective (in the same case). Three such phrases are: *''sensu stricto'' – "in the strict sense", abbreviation ''s.s.'' or ''s.str.''; *''sensu lato'' – "in the broad sense", abbreviation ''s.l.''; *''sensu amplo'' – "in a relaxed, generous (or 'ample') sense", a similar meaning to ''sensu lato''. Søren Kierkegaard uses the phrase ''sensu eminenti'' to mean "in the pre-eminent r most important or significantsense". When appropriate, comparative and superlative adjectives may also be used to convey the meaning ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
UCLA
The University of California, Los Angeles (UCLA) is a public land-grant research university in Los Angeles, California. UCLA's academic roots were established in 1881 as a teachers college then known as the southern branch of the California State Normal School (now San José State University). This school was absorbed with the official founding of UCLA as the Southern Branch of the University of California in 1919, making it the second-oldest of the 10-campus University of California system (after UC Berkeley). UCLA offers 337 undergraduate and graduate degree programs in a wide range of disciplines, enrolling about 31,600 undergraduate and 14,300 graduate and professional students. UCLA received 174,914 undergraduate applications for Fall 2022, including transfers, making the school the most applied-to university in the United States. The university is organized into the College of Letters and Science and 12 professional schools. Six of the schools offer undergraduate degre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blaire Van Valkenburgh
Blaire Van Valkenburgh is an American paleontologist and holds the Donald R. Dickey Chair in Vertebrate Biology in the Department of Ecology and Evolutionary Biology at University of California Los Angeles. She is a former president of Society of Vertebrate Paleontology. Early life and education Van Valkenburgh was born in Washington, D.C. and raised in Alexandria, Virginia. Her mother, Lois Van Valkenburgh, was a civil rights activist. From 1964 to 1970, she attended T. C. Williams High School. Van Valkenburgh received a bachelor's degree from Stockton State College in New Jersey in 1974, a Ph.D. in Vertebrate Paleobiology from Johns Hopkins University in 1984, where she worked with Robert Bakker, after which she worked as a postdoctoral fellow with Alan Walker at Johns Hopkins before moving to UCLA in 1986. Career Van Valkenburgh is a paleontologist and holds the Donald R. Dickey Chair in Vertebrate Biology in the Department of Ecology and Evolutionary Biology at Universi ... [...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] |
Canid
Canidae (; from Latin, ''canis'', "dog") is a biological family of dog-like carnivorans, colloquially referred to as dogs, and constitutes a clade. A member of this family is also called a canid (). There are three subfamilies found within the canid family, which are the extinct Borophaginae and Hesperocyoninae, and the extant Caninae. The Caninae are known as canines, and include domestic dogs, wolves, coyotes, foxes, jackals and other extant and extinct species. Canids are found on all continents except Antarctica, having arrived independently or accompanied human beings over extended periods of time. Canids vary in size from the gray wolf to the fennec fox. The body forms of canids are similar, typically having long muzzles, upright ears, teeth adapted for cracking bones and slicing flesh, long legs, and bushy tails. They are mostly social animals, living together in family units or small groups and behaving cooperatively. Typically, only the dominant pair in a group breed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caninae
The Caninae, known as canines, are one of three subfamily, subfamilies found within the Canidae, canid family. The other two canid subfamilies are the extinct Borophaginae and Hesperocyoninae. The Caninae includes all living canids and their most recent fossil relatives. Their fossils were first found in North America and dated to the Oligocene era, then spreading to Asia at the end of the Miocene era, some 7 million to 8 million years ago. Taxonomy and lineage The genus ''Leptocyon'' (Greek: ''leptos'' slender + ''cyon'' dog) includes 11 species and was the first primitive canine. They were small and weighed around 2 kg. They first appeared in Sioux County, Nebraska in the Orellan era 34-32 million years ago, which was the beginning of the Oligocene. This was the same time as the appearance of the Borophaginae with whom they share features, indicating that these were two sister groups. Borophaginae skull and dentition were designed for a powerful killi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Borophaginae
The extinct Borophaginae form one of three subfamilies found within the canid family. The other two canid subfamilies are the extinct Hesperocyoninae and extant Caninae. Borophaginae, called "bone-crushing dogs", were endemic to North America during the Oligocene to Pliocene and lived roughly 34—2.5 million years ago, existing for about . Origin The Borophaginae descended from the subfamily Hesperocyoninae. The earliest and most primitive borophagine is the genus ''Archaeocyon'', which is a small fox-sized animal mostly found in the fossil beds in western North America. The borophagines soon diversified into several major groups. They evolved to become considerably larger than their predecessors, and filled a wide range of niches in late Cenozoic North America, from small omnivores to powerful, bear-sized carnivores, such as ''Epicyon''. Species There are 66 identified borophagine species, including 18 new ones that range from the Orellan to Blancan ages. A phylogenetic anal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hesperocyoninae
The extinct Hesperocyoninae are one of three subfamilies found within the canid family. The other two canid subfamilies are the extinct Borophaginae and extant Caninae. Taxonomic history Hesperocyoninae are basal canids that gave rise to the other two canid subfamilies, the Borophaginae and Caninae. This subfamily was endemic to North America, living from the Duchesnean stage of the Late Eocene through to the early Barstovian stage of the Miocene, lasting around 20 million years. It comprises 10 recognized genera and 26 recognized species. Four major lineages can be defined based on shared characteristics: *''Mesocyon''-''Enhydrocyon'' clade (includes ''Cynodesmus, Sunkahetanka, Philotrox'') *''Osbornodon'' clade *'' Paraenhydrocyon'' *'' Ectopocynus clade'' The genus ''Caedocyon'', which is only known from a single partial cranium that shows some ''Paraenhydrocyon'' affinities, probably represents another independent lineage. ''Hesperocyon'', which lacks the shared derived c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Canidae
Canidae (; from Latin, ''canis'', "dog") is a biological family of dog-like carnivorans, colloquially referred to as dogs, and constitutes a clade. A member of this family is also called a canid (). There are three subfamilies found within the canid family, which are the extinct Borophaginae and Hesperocyoninae, and the extant Caninae. The Caninae are known as canines, and include domestic dogs, wolves, coyotes, foxes, jackals and other extant and extinct species. Canids are found on all continents except Antarctica, having arrived independently or accompanied human beings over extended periods of time. Canids vary in size from the gray wolf to the fennec fox. The body forms of canids are similar, typically having long muzzles, upright ears, teeth adapted for cracking bones and slicing flesh, long legs, and bushy tails. They are mostly social animals, living together in family units or small groups and behaving cooperatively. Typically, only the dominant pair in a group bree ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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