A finger or toe; a digit.
Darwinian / Darwinism
Of or relating to the research and theories of Charles Darwin (English naturalist, 1809-1882) especially the proposition that the presence of many diverse species on earth is the result of the survival of those individual organisms whitin a given species whose traits are more likely to ensure reproductive success, and the consequent dying out of those individuals with less favorable traits. This reinforcement of favorable traits leads to divergence within the species and ultimately to the origin of new species. Thus Darwinism. See also natural selection
In the process of species development, a recognizable new species that evolves from a parent species.
To rot, disintegrate
Any activity engaged in by an animal to avoid falling prey to a predator.
Describing a pattern in which the rate of a biological phenomenon (e.g., reproduction) is affected by population density, either the number of individuals of an organism\'s own species or those of other species, or both. For example, the birth rate in a density-dependent group will tend to decrease as the surrounding population expands, and tend to increase as it declines.
Describing a pattern in which the rate of a biological phenomenon (e.g., reproduction) is independent of the population density of the environment.
A distinctive tooth pattern in which a large number of small, slender individual teeth are wedged very tightly together along the length of the jaw, with multiple teeth stacked in one tooth position.
The lower jawbone; this bone often bears the teeth of the lower jaw.
Bone in the mandible
A small tooth or toothlike structure
Dentin / Dentine
A hard, bonelike tissue that is the main substance of teeth.
The type, number or arrangement of the teeth.
The chemical process (which can severly damage fossil specimens) whereby iron pyrites spontaneously converts into iron sulphate and acids.
1. In general, nor original; coming later.
2. Describing a character or distinguishing feature altered from an earlier form of a species or other taxonomic group.
Relating to the dermis or to the skin in general.
Bone formed within the skin.
The inner layer of the skin, beneath the epidermis.
Describes a species or taxon that has evolved from another species or from within a taxon
The various processes affecting deposits and organic remains after deposition and before recovery.
The shaft of a long bone; the portion of a bone between the extremities (epiphyses).
A natural glass formed by shock pressure from any of several minerals without melting. It is found only in association with meteorite impact craters.
(\"two holes\") One of the Diapsida, a group of reptiles distinguished by the presence of two openings in the side of the skull behind the orbit (eye socket); contrasted with the synapsids (one such skull opening) and the anapsids (no opening); the group includes pterosaurs, dinosaurs, marine reptiles, crocodiles, birds, lizards, and snakes.
Curious pig-like therapsids of the Permian and Triassic Periods., often with just two tusks in the upper jaw.
The study of the structure of a crystal by observing the changes in amplitude or phase of an X-ray beam or other energy waves penetrating its structure.
A finger, toe or other such homologous structure
Walking (or running) with the weight supported along the length of the toes or digits, while the hind part of the foot in more or less raised off the ground; the pattern of many four-legged animals; eg., the modern canines and felines. Compare plantigrade, unguligrade.
The existence of two distinct genetically determined forms of the same species, such as distinct male and female forms or distinct young and mature forms.
Clade of animals, partly distinguished by a largely to fully open acetabulum, that first evolved in the latter third of the Triassic and was the dominant land animal from the early Jurassic to the end of the Cretaceous. Dinosaurs were wholly terrestrial, with no known aquatic species. Only one major clade of dinosaurs, Aves (\"birds\"), survives today. The name means \"fearsome great lizards\".
A name proposed by Dave Russell for a theoretical modern dinosaur with a human-like body form, based on a model of extrapolated or projected evolution since the end of Mesozoic time.
The trampling of the soil surface or subsurface by dinosaurs, especially by large herbivorous dinosaurs. See also bioturbation.
A process of natural selection in which variation is selected for, resulting in a character change in one direction in the overall genetic makeup of a population
Pulled apart, broken up
The process of spreading out, in a geographic sense.
Any body feature or pattern of behavior that acts as a physical signal or indicator to others, either of the same species or other species.
A process of natural selection in which extremes are selected for, while intermediate examples are selected against, thus resulting in divergent subpopulations. Compare stabilizing selection
1. Describes a feature anatomically located away from the central part of the body, or away from a point of attachment or origin
2. In anatomy, far away from the center or the attached end; outer, 3. far apart; widely spaced.
The total geographic range in which a given species or group occurs.
The scientific study of the distribution of a given catagory of organisms through time and space.
Of an organism, primarily or exclusively active in the daytime.
Moving away from, changing in form in any evolutionary sense.
1. The fact of being diverse; existing in a variety of forms or types; e.g., a wide variety of different species.
2. a measurement of the number of species and their population size within a given community.
Diverticulum / plural Diverticula
An enclosed sac that can either occur normally or be caused by the herniation of the mucous membrane through a weakness or defect in the muscular wall of a tubular organ; e.g., the intestine
Deoxyribonucleic acid, the complex chemical substance within the cells of a living organism that contains or forms the genetic (hereditary) information for the organism.
Dominance / Dominant
1. The fact of a particular species having a more significant effect on the ecological conditions of its environment than any of the other species present there, because of its greater population, body size, aggressiveness, or other such factors.
2. The fact of an individual within a species group having higher status than others of the group in choice, food, mates, living space, and so on. 3. The fact of one altenate form of a gene tending to mask the expression of the other corresponding form. Thus, dominant
1. Describes a feature anatomically located on, in or near the back 2.Relating to the back or upper side of an animal or body part.