Geologic time scaleSystem that relates geologic strata to timeThe geologic time scale.The geologic time scale or geological time scale describes how geologic time is divided into standardised intervals. It uses the rock record together with the principles of chronostratigraphy to place rock sequences into their relative age positions, and geochronology techniques, such as radiometric dating, to precisely date the boundaries between them.
ExoskeletonAn exoskeleton (from Ancient Greek (éxō)'outer' and (skeletós)'skeleton') is a skeleton that is on the exterior of an animal in the form of hardened integument, which both supports the body's shape and protects the internal organs, in contrast to an internal endoskeleton (e.g. that of a human) which is enclosed underneath other soft tissues. Some large, hard and non-flexible protective exoskeletons are known as shell or armour.
EvolutionChange in the heritable characteristics of populationsEvolution is the change in the heritable characteristics of biological populations over successive generations. It happens when individuals in a population vary in their genetic characteristics and in the numbers of their surviving offspring.
SeashellA seashell (or sea shell), also known simply as a shell, is a hard, protective outer layer usually created by an animal or organism that lives in the sea. Most seashells are made by mollusks, such as snails, clams, and oysters to protect their soft insides. Empty seashells are often found washed up on beaches by beachcombers. The shells are empty because the animal has died and the soft parts have decomposed or been eaten by another organism.
Petrified woodPetrified wood is the name given to a special type of fossilized wood, the fossilized remains of terrestrial vegetation. Petrifaction (from Ancient Greekπέτρα meaning 'rock' or 'stone'), is the result of a tree or tree-like plants having been replaced by stone via a mineralization process that often includes permineralization and replacement.
PaleontologyStudy of past life through fossilsBust of the paleontologist Georges Cuvier (left) and a cast skeleton of Palaeotherium magnum (named by Cuvier in 1804, right), Cuvier Museum of MontbéliardPaleontology or palaeontology is the scientific study of the life of the past, mainly but not exclusively through the study of fossils.
HairHair is a protein filament that grows from follicles found in the dermis. Hair is one of the distinguishing characteristics of mammals. The human body, apart from areas of glabrous skin, is covered in follicles which produce thick terminal and fine vellus hair. Most common interest in hair is focused on hair growth, hair types, and hair care, but hair is also an important biomaterial primarily composed of protein, notably alpha-keratin.
BoneA bone is a rigid organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the organs of the body, produce red and white blood cells, store minerals, help regulate acid-base homeostasis, provide structure and support for the body, and enable mobility and hearing. Bones come in a variety of shapes and sizes and have complex internal and external structures.
StratumIn geology and related fields, a stratum (pl.: strata) is a layer of rock or sediment characterized by certain lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by visible surfaces known as either bedding surfaces or bedding planes.
DNAMolecule that carries genetic informationThe structure of the DNA double helix (type B-DNA). The atoms in the structure are colour-coded by element and the detailed structures of two base pairs are shown in the bottom right.Simplified diagramDeoxyribonucleic acid (pronunciation; DNA) is a polymer composed of two polynucleotide chains that coil around each other to form a double helix.
Classical LatinClassical Latin is the form of Latin recognized as a literarystandard by writers of the late Roman Republic and early Roman Empire. It developed around 75 BC from Old Latin, and developed by the 3rd century AD into Late Latin. In some later periods, the former was regarded as good or proper Latin, while the latter was seen as debased, degenerate, or corrupted.
MicroorganismMicroscopic living organismA cluster of Escherichia coli bacteria magnified 10,000 timesA microorganism, or microbe, is an organism of microscopic size, which may exist in its single-celled form or as a colony of cells. The possible existence of unseen microbial life was suspected from antiquity, with an early attestation in Jain literature authored in 6th-century BC India.*As an Amazon Associate I earn from qualifying purchases.