Glossary of Biological and Paleontological Terms
(Compiled by Charles J Vella, PhD: thanks to Wikipedia, Smithsonian, etc.)
Acquired trait: A phenotypic characteristic, acquired during growth and development, that is not genetically based and therefore cannot be passed on to the next generation (for example, the large muscles of a weightlifter).
Adaptation: An adaptation is a feature produced by natural selection for its current function.
Adaptive radiation: The diversification, over evolutionary time, of a species or group of species into several different species or subspecies that are typically adapted to different ecological niches (for example, Darwin's finches).
Advanced (synonym: derived; opposite: primitive): In phylogenetic studies, an organism or character further removed from an evolutionary divergence than a more primitive one.
Allele: A known variation (version) of a particular gene
Allen's Rule: Within species of warm-blooded animals (birds + mammals) those populations living in colder environments will tend to have shorter appendages than populations in warmer areas.
Allometry: The relation between the size of an organism and the size of any of its parts. For example, an allometric relation exists between brain size and body size, such that (in this case) animals with bigger bodies tend to have bigger brains.
Allopatric speciation: Speciation following geographical isolation of subpopulations of the species.
Analogous structures: Structures in different species that look alike or perform similar functions (e.g., the wings of butterflies and the wings of birds) that have evolved convergently but do not develop from similar groups of embryological tissues, and that have not evolved from similar structures known to be shared by common ancestors. Contrast with homologous structures.
Ancestral homology: Homology that evolved before the common ancestor of a set of species, and which is present in other species outside that set of species. Compare with derived homology.
Anthropoid: A member of the group of primates made up of monkeys, apes, and humans.
Apomorphy: a characteristic that is different form the form of an ancestor, i.e., an innovation, of use in determining membership in a clade. In other words, it is an apomorphy shared by members of a monophyletic group, and thus assumed to be present in their most recent common ancestor. A derived trait is an apomorphy, which means a trait that has changed since the time of a common ancestor.
Artificial selection: The process by which humans breed animals and cultivate crops to ensure that future generations have specific desirable characteristics. In artificial selection, breeders select the most desirable variants in a plant or animal population and selectively breed them with other desirable individuals
Australopithecus: The extinct genus of Plio-Pleistocene hominids found in South and East Africa. The evolutionary link between apes and humans.
Australopithecine: A group of bipedal hominid species belonging to the genus Australopithecus that lived between 4.2 and 1.4 mya.
Australopithecus afarensis: An early australopithecine species that was bipedal; known fossils date between 3.6 and 2.9 mya (for example, Lucy).
Bergmann's Rule: Northern races of mammals and birds tend to be larger than Southern races of the same species.
Biological species concept: The concept of species, according to which a species is a set of organisms that can interbreed among each other. Compare with cladistic species concept, ecological species concept, phenetic species concept, and recognition species concept.
Bipedal: Habitually walking upright on two legs
Bottleneck: A drastic reduction in the population size followed by an expansion. This often results in altered gene pool as a result of subsequent genetic drift.
Brow ridge: Bony ridge above the eye sockets
Catalogue number: Sometimes also called a field number, this is the number given a fossil by the researcher during the time of discovery. Catalogue numbers usually consist of a location abbreviation (i.e. 'OH' standing for 'Olduvai Hominid') followed by a number assigned to the fossil, normally in the order that it was found. So OH5 is the fifth hominid that was found at Olduvai Gorge.
Catarrhini: One of the two divisions (suborder) of Primates containing the old world monkeys and apes (extinct and extant). The other division is Platyrrhini (new world monkeys).
Clade: A clade (from AncientGreek: κλάδος, klados, "branch") is a group of organisms that consists of a common ancestor and all its lineal descendants, and represents a single "branch" on the "tree of life". All descendants of any given species. A single whole branch of a phylogeny.Synonym of monophyletic group.
Cladistics: Cladistics (from Greek κλάδος, klados, i.e., "branch") is an approach to biological classification in which organisms are categorized based on shared derived characteristics that can be traced to a group's most recent common ancestor and are not present in more distant ancestors. Therefore, members of a group are assumed to share a common history and are considered to be closely related. In terms of strict cladistical analysis, the age of the fossils does not matter. Cladistics establishes evolutionary relationships strictly by grouping organisms according to their shared-derived characteristics. In the case of paleontology, the characteristics are almost always morphological, but in living organisms, the traits may be behavioral or genetic as well.
Cladogram: A branching diagram that illustrates hypotheses about the evolutionary relationships among groups of organisms. Cladograms can be considered as a special type of phylogenetic tree that concentrates on the order in which different groups branched off from their common ancestors. A cladogram branches like a family tree, with the most closely related species on adjacent branches.
Co-evolution: Joint evolution of two unrelated species that have a close ecological relationship resulting in reciprocal adaptations as happens between host and parasite, and plant and insect.
Convergent evolution: independent evolution of similar features in species of different lineages. Convergent evolution creates analogous structures that have similar form or function but were not present in the last common ancestor of those groups. Same as homoplasy. Evolution of two or more different lineages towards similar morphology due to similar adaptive pressures. Examples of convergence are: fins or fin-like structures in fish, cuttlefish and whales; extreme similarity in alarm calls by five small birds; endothermy in dogs and ducks, wings of butterflies and birds.
Coprolite: The fossilized waste (dung; fecies) matter of animals.
Core: In stone tool terminology, a source stone reduced in size by the intentional removal of flakes
Cranial: Refers to a bone of the cranium, which is part of the skull (but does not include the mandible).
Creationism: The religious doctrine that all living things on Earth were created separately, in more or less their present form, by a supernatural creator, as stated in the Bible; the precise beliefs of different creationist groups vary widely.
Darwinian evolution: Evolution by the process of natural selection acting on random variation.
Darwinism: Darwin's theory that species originated by evolution from other species and that evolution is mainly driven by natural selection. Differs from neo-Darwinism mainly in that Darwin did not know about Mendelian inheritance.
Dental microwear: Dental microwear is the study of the microscopic wear on a tooth's surface that occurred as a direct result of use (chewing). Dental microwear studies look for tooth scratches and pits that occur on teeth predominantly through chewing, and can provide evidence of what an individual ate in the past.
Derived: A derived character is a character that is derived from an ancestral character over evolutionary history; a newer characteristic; in phylogenetics, a derived character of a clade that has been inherited from a common ancestor and distinguishes the clade from other potentially related organisms is called a "synapomorphy," a shared ("syn") character that sets the clade apart ("apo")
Diastema: A diastema is space between two teeth. In paleoanthropology, scientists look at the space between the lower canine teeth and first premolars where the upper canine fits as a common characteristic of apes, who have larger canines than humans.
Divergent evolution: A kind of evolutionary change that results in increasing morphological difference between initially more similar lineages.
Ecological species concept: A concept of species, according to which a species is a set of organisms adapted to a particular, discrete set of resources (or "niche") in the environment.
Endocast: An endocast is a cast that shows the brain's impression on the inside of the skull. Endocasts can be artificially made by spreading a mold into an empty skull to represent the skull's brain. The artificial brain is then removed to show the brain's impression, or lines and ridges on its outside surface, that formed against the skull's inside. Endocasts can also form naturally by sediments filling up the inside of an empty skull and fossilizing.
Environmental variability hypothesis: The hypothesis that adaptation to a variable environment, rather than a static environment or directional change, has characterized human evolution
Epigenetics: The study of heritable changes in gene expression that occur without a change in DNA sequence.
Evolution: Descent with modification. The process that results in heritable changes in a population spread over many generations (change in allele frequencies over time). Biological evolution refers to populations and not to individuals and that the changes must be passed on to the next generations. Genes mutate, individuals are selected, and populations evolve.
Evolutionary Developmental Biology (Evo-Devo): The branch of evolutionary biology studying the relationships between changes in developmental pathways due to mutations in regulatory parts of genes and evolutionary changes (macroevolution). The emphasis is on the changes in expression patterns of the genes involved in developmental pathways rather than structural changes in genes.
Extinction: The disappearance of a species or a population.
Fauna: animals that are characteristic of a certain age, locality, or formation.
Fitness: Lifetime reproductive success of an individual (i.e., the total number of offspring who themselves survive to reproduce). It can be seen as the extent to which an individual successfully passes on its genes to the next generation. It has two components: survival (viability) and reproductive success (fecundity). Variation in fitness is the major driving force in biological evolution. The success of an individual (or allele or genotype in a population) in surviving and reproducing, measured by that individual's (or allele's or genotype's) genetic contribution to the next generation and subsequent generations.
Flake: A sharp piece of stone intentionally removed from a core
Flora: Plant life; often used to distinguish from animal life ("fauna").
Foramen magnum: The foramen magnum is the hole at the base of the skull through which the spinal cord enters into the skull and connects to the brain. This hole is one of the key ways scientists can tell the difference between a bipedal human skull and the skull of a quadrupedal great ape. In humans, the foramen magnum is underneath the skull, allowing humans to hold their head upright and look forward. In a great ape, where the ape’s head rests in front of the neck instead of on top, the foramen magnum is positioned at the rear of the head so its eyes face forward, and not down, as it moves.
Fossil: A preserved trace of a once-living organism. A fossilized bone occurs when the living (organic) cells and tissue have become replaced with external minerals while buried in the ground. Virtually all early human fossils are bones in which this process of mineral replacement has taken place. Footsteps can be fossilized.
Fossil record: the history of life on Earth through geological time, as preserved through fossil remains in sedimentary rock (sometimes referred to poetically in older books as the record of the rocks). Also the fossil history of any particular group.
Fossilization: All the processes that involve the burial of a plant or animal in sediment and the eventual preservation of all, part, or a trace of it
Founder effect (Sewall Wright effect): A type of genetic drift in which allele frequencies are altered in a small population, which is a nonrandom sample of a larger (main) population.
Gene flow: The movement of genes within a population or between two populations following genetic admixture. Gene flow creates new combinations of genes or alleles in individuals that can be tested against the environment. This way it is one of the sources of variation in the process of natural selection.
Genetic drift: Evolutionary change over generations due to random events in small populations (not to be mixed with sampling error due to a small sample size). It operates unless overcome by strong selective forces. Changes in the frequencies of alleles in a population that occur by chance, rather than because of natural selection.
Genetic fitness: Classic genetic fitness is the average direct reproductive success of an individual possessing a specific genotype in comparison to others in the population. Inclusive fitness is described as the classic fitness plus the probability that an individual's genotype may be passed on through relatives.
Genotype: The set of two genes possessed by an individual at a given locus. More generally, the genetic profile of an individual.
Genus: is a taxonomic rank used in the biological classification of living and fossil organisms in biology. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclature, the genus name forms the first part of the binomial species name for each species within the genus. i.e. Homo sapiens – sapiens is a genus in the species Homo
Geological timescale: The period between the origin of earth (4,500 Mya) and the beginning of the Cambrian period (540 Mya) is called the Precambrian Eon. The last 540 million years (Phanerozoic Eon) are divided into three eras: Palaeozoic (540-245 Mya); Mesozoic (245-65 Mya); Cainozoic. The geological periods (included in an era, longer than an epoch) are as follows: Vendian (immediately before the Cambrian; 610-540 Mya); Cambrian (540-510 Mya); Ordovician; Silurian; Devonian; Carboniferous; Permian; Triassic / Jurassic / Cretaceous (altogether the Mesozoic Era); Tertiary (65-1.64 Mya) and Quaternary. An epoch is a subdivision of a period
Glaciation: The formation of large sheets of ice across land. Glaciation of the continents marks the beginning of ice ages, when the makeup of Earth and organisms on it changes dramatically.
Great Apes: Chimpanzees (including bonobos), gorillas, and orangutans.
Hammerstone: Cobble used to strike flakes from a stone core
Holocene: An epoch of the Quaternary period, spanning the time from the end of the Pleistocene (10,000 years ago) to the present. The most recent period of geologic history, which extends from 10,000 years ago to the present.
Holotype: Similar to a ‘type specimen,’ for fossil species, the ‘holotype’ of a species is the fossil specimen used when the species is formally described.
Hominid: Refers to the evolutionary group of great apes, including living Asian great apes (orangutans), living African great apes (chimpanzees, bonobos, and gorillas), and humans. This word comes from Hominidae, a formal biological term that is more specific than Hominoidea (= all apes – the great apes and the lesser apes, which include gibbons and siamangs). Some researchers still use the word hominid to refer to the human evolutionary group alone (what we call hominin). This usage goes back to the tradition when humans (hominids) were considered completely divided from all great apes (pongids).
Hominin: Refers to the human evolutionary group of species, including fossil and modern. This word comes from Hominini, a formal biological term in between the level of genus (e.g., Homo, Australopithecus, etc.) and the level of family (Hominidae).
Homologous structures: The structures shared by a set of related species because they have been inherited, with or without modification, from their common ancestor. For example, the bones that support a bat's wing are similar to those of a human arm.
Homology: A similarity due to inheritance from a common ancestor.A character shared by a set of species and present in their common ancestor. Compare with analogy.
Homo erectus: A species of hominid that lived between 1.8 mya and 300,000 years ago; the first Homo species to migrate beyond Africa.
Homo habilis: A species of hominid that lived between 1.9 and 1.8 mya, the first species in genus Homo, and the first hominid associated with clear evidence of tool manufacture and use.
Homo neanderthalensis: A species of hominid that lived between 150,000 and 30,000 years ago in Europe and Western Asia, originally thought to be a geographic variant of Homo sapiens but now generally accepted to be a distinct species.
Homo sapiens: Modern humans, which evolved to their present form about 100,000 years ago.
Homoplasy: a character state that is shared by two or more taxa due to some cause other than common ancestry.The two main types of homoplasy are convergence (evolution of the "same" character in at least two distinct lineages) and reversion (the return to an ancestral character state)
Humerofemoral index: The humerofemoral index is measure comparing arm length to leg length. The index is defined by the arm length divided by the leg length times 100. Modern apes and chimpanzees have arms and legs that are almost the same size in length, giving them a humerfoemoral index of about 100. Humans, with shorter arms than legs, have a humerofemoral index of about 70.
Hypothesis: A proposed, testable scientific explanation for a particular set of phenomena
Inheritance of acquired characters: Historically influential but factually erroneous theory that an individual inherits characters that its parents acquired during their lifetimes. Lamarckian inheritance.
In situ: The words 'in situ' are Latin meaning 'in the place.' In prehistoric studies, in situ refers to an artifact or fossil that has not been taken out of the original location where it was found. In situ materials are undisturbed, which allows archaeologists to date them and/or give them better context by looking at what artifacts or sediments are found nearby.
Intelligent design: The non-scientific argument that complex biological structures have been designed by an unidentified supernatural or extraterrestrial intelligence.
Land bridge: A connection between two land masses, especially continents (e.g., the Bering land bridge linking Alaska and Siberia across the Bering Strait) that allows migration of plants and animals from one land mass to the other.