Richard Steven Valenzuela, known professionally as Ritchie Valens, was an American guitarist, singer and songwriter. A rock and roll pioneer and a forefather of the Chicano rock movement, Valens was killed in a plane crash eight months into his music career.
Stygimys is an extinct mammal genus from the Upper Cretaceous and Paleocene of North America. It was a member of the extinct order Multituberculata within the suborder Cimolodonta, family Eucosmodontidae.
HeLa is an immortalized cell line used in scientific research. It is the oldest and most commonly used human cell line. The line is derived from cervical cancer cells taken on February 8, 1951, from Henrietta Lacks, a 31-year-old African-American mother of five, who died of cancer on October 4, 1951, and after whom they are named. The cell line was found to be remarkably durable and prolific, which allows it to be used extensively in scientific study.
In biology, adaptation has three related meanings. Firstly, it is the dynamic evolutionary process of natural selection that fits organisms to their environment, enhancing their evolutionary fitness. Secondly, it is a state reached by the population during that process. Thirdly, it is a phenotypic trait or adaptive trait, with a functional role in each individual organism, that is maintained and has evolved through natural selection.
Foster's rule, also known as the island rule or the island effect, is an ecogeographical rule in evolutionary biology stating that members of a species get smaller or bigger depending on the resources available in the environment. For example, it is known that pygmy mammoths evolved from normal mammoths on small islands. Similar evolutionary paths have been observed in elephants, hippopotamuses, boas, sloths, deer and humans. It is part of the more general phenomenon of island syndrome which describes the differences in morphology, ecology, physiology and behaviour of insular species compared to their continental counterparts.
Condylarthra is an informal group – previously considered an order – of extinct placental mammals, known primarily from the Paleocene and Eocene epochs. They are considered early, primitive ungulates. It is now largely considered to be a wastebasket taxon, having served as a dumping ground for classifying ungulates which had not been clearly established as part of either Perissodactyla or Artiodactyla, being composed thus of several unrelated lineages.
Leigh Van Valen was a U.S. evolutionary biologist. At the time of his death, he was professor emeritus in the Department of Ecology and Evolution at the University of Chicago.
In evolutionary biology, an evolutionary arms race is an ongoing struggle between competing sets of co-evolving genes, phenotypic and behavioral traits that develop escalating adaptations and counter-adaptations against each other, resembling an arms race. These are often described as examples of positive feedback. The co-evolving gene sets may be in different species, as in an evolutionary arms race between a predator species and its prey, or a parasite and its host. Alternatively, the arms race may be between members of the same species, as in the manipulation/sales resistance model of communication or as in runaway evolution or Red Queen effects. One example of an evolutionary arms race is in sexual conflict between the sexes, often described with the term Fisherian runaway. Thierry Lodé emphasized the role of such antagonistic interactions in evolution leading to character displacements and antagonistic coevolution.
Purgatorius is a genus of seven extinct eutherian species typically believed to be the earliest example of a primate or a proto-primate, a primatomorph precursor to the Plesiadapiformes, dating to as old as 66 million years ago. The first remains were reported in 1965, from what is now eastern Montana's Tullock Formation, specifically at Purgatory Hill in deposits believed to be about 63 million years old, and at Harbicht Hill in the lower Paleocene section of the Hell Creek Formation. Both locations are in McCone County, Montana.
Oxyaenidae is a family of extinct carnivorous placental mammals. Traditionally classified in order Creodonta, this group is now classified in its own order Oxyaenodonta within clade Pan-Carnivora in mirorder Ferae. The group contains four subfamilies comprising fourteen genera. Oxyaenids were the first to appear during the late Paleocene in North America, while smaller radiations of oxyaenids in Europe and Asia occurred during the Eocene.
Isadore Nabi was a pseudonym used by a group of scientists including Richard Lewontin, Richard Levins, Robert MacArthur, and Leigh van Valen in the 1960s. Inspired by the work of Nicolas Bourbaki, they allegedly hoped to create a unified approach to evolutionary biology. However, the project was aborted and the name was reused in the 1980s for satirical purposes.
A Darwinian Left: Politics, Evolution and Cooperation is a 1999 book by the philosopher Peter Singer. In the book, Singer argues that the view of human nature provided by evolutionary science, particularly by evolutionary psychology, is compatible with the ideological framework of the Left and should be incorporated into it.
Nils Christian Stenseth is a Norwegian biologist with a focus on ecology and evolution. He is the director of the Centre for Ecological and Evolutionary Synthesis (CEES) at the University of Oslo, CEES was given Centre of Excellence status by the Research Council of Norway in December 2006. He is also the Chief Scientist at the Norwegian Institute of Marine Research in Norway, and Honorary Professor of Tsinghua University.
The Red Queen hypothesis is a hypothesis in evolutionary biology proposed in 1973, that species must constantly adapt, evolve, and proliferate in order to survive while pitted against ever-evolving opposing species. The hypothesis was intended to explain the constant (age-independent) extinction probability as observed in the paleontological record caused by co-evolution between competing species; however, it has also been suggested that the Red Queen hypothesis explains the advantage of sexual reproduction at the level of individuals, and the positive correlation between speciation and extinction rates in most higher taxa.
Ankalagon saurognathus is an extinct carnivorous mammal of the family Mesonychidae, endemic to North America during the Paleocene epoch, existing for approximately 3.1 million years.
Ictidopappus is an extinct genus of mammals from extinct subfamily Ictidopappinae within extinct family Viverravidae, that lived in North America during the early Paleocene.
Kharmerungulatum is an extinct genus of herbivorous mammal from the Late Cretaceous (Maastrichtian) Intertrappean Beds of Madhya Pradesh, India. Its specific epithet honors Leigh Van Valen. It was described as one of the earliest known condylarths.
Palaeoryctidae or Palaeoryctoidea is an extinct group of relatively non-specialized non-placental eutherian mammals that lived in North America during the late Cretaceous and took part in the first placental evolutionary radiation together with other early mammals such as the leptictids. Some sources classified the Palaeoryctidae as a superfamily.
Macropetalichthys is a genus of placoderm fish, named by Norwood and Owen in 1846; the name "Macropetalichthys" means "armour-plated fish". It was assigned to Arthrodira by Woodward (1891); and to Petalichthida by Sepkoski (2002). It contains a single species, M. rapheidolabis.
A biological rule or biological law is a generalized law, principle, or rule of thumb formulated to describe patterns observed in living organisms. Biological rules and laws are often developed as succinct, broadly applicable ways to explain complex phenomena or salient observations about the ecology and biogeographical distributions of plant and animal species around the world, though they have been proposed for or extended to all types of organisms. Many of these regularities of ecology and biogeography are named after the biologists who first described them.
