Over 200 years ago, Swedish naturalist Karl von Linne (or, as he Latinized the name, Carolus Linneaus) devised a system for classifying all living things based on anatomical structures. Although Linneaus lived before Darwin, his method presaged later concepts of evolution that saw shared characteristics as evidence of common descent. Some modern taxonomists feel his system does not adequately reflect evolutionary relationships, but their proposed replacement, called PhyloCode, is still controversial.
In the Linnean system, every animal, plant, and single-celled organism is assigned to a species. A biological species is a population whose members can breed with each other but not with other populations.
A group of closely related species forms a genus (plural, genera). The name of each species contains two parts, with the genus capitalized (Homo), the species name in lowercase (sapiens), and both italicized. Most such binomials are derived from Latin. Some genera, like our own, contain only one living species; others are much more diverse.
Higher categories, or taxa, combine genera into families, families into orders, orders into phyla. All life forms are assigned to one of five kingdoms. Here’s how if works for one well-known group of animals:
Kingdom: Animalia (mobile multicellular organisms)
Phylum: Chordata (animals with a flexible skeletal rod, the notochord)
Subphylum: Vertebrata (chordates with backbones)
Superclass: Tetrapoda (vertebrates with four limbs)
Class: Mammalia (tetrapods with mammary glands)
Order: Carnivora (mammals with cheek teeth modified for shearing flesh)
Family: Canidae (carnivores with long legs, four-toed feet, and non-retractile claws)
Genus: Canis (wolves and relatives)
Species: Canis familiaris (domestic dog); Canis lupus (gray wolf); Canis latrans (coyote)
For an overview of the Miocene, visit the UC Museum of Paleontology
For local prehistory, the Mount Diablo Interpretive Association has information on the Trail Through Time and a road log for the mountain’s geology.