The name given to a particular female hominid (of the species Australopithecus afarensis) who lived in what is now Ethiopia about three million years ago. “Lucy” is famous because she left behind a very complete fossilized skeleton found in 1974.

Long life; long duration of existence.

The standard system of classification in which every organism is assigned a kingdom, phylum, class, order, family, genus, and species. This system groups organisms into ever smaller and smaller groups (like a series of boxes within boxes, called a nested hierarchy).

Traits that make up the life cycle of an organism. An organism’s life history includes characteristics related to reproduction, development, and growth (e.g., fecundity, types of larval stages passed through, size at adulthood, and habitats used at different points in the life cycle).

An area where animals congregate to perform courtship displays and select mates.

The period about 600 million years after the Solar System started to form (early in the Solar System’s history, but “late” in its formation) when the rate of collisions between bodies was much higher than it is now.

A phylogenetic tree in which the most taxon-rich clades are consistently positioned to the right of less diverse clades on vertically-oriented trees or above less diverse clades on horizontally-oriented trees.

An event in which a single historical lineage gives rise to two or more descendent lineages. Every node on a phylogeny is a lineage-splitting event.

The place in the DNA where a gene is located. For example, the pea color locus is the place in a pea plant’s DNA that determines what the color of the peas will be. The pea color locus may contain DNA that makes the peas yellow or DNA that makes the peas green — these are called the yellow and green alleles.

A continuous line of descent; a series of organisms, populations, cells, or genes connected by ancestor/descendent relationships.