Chapter 25 Flashcards
Amniotes
Mammals, reptiles, and their extinct close relatives. Characterized by many adaptations to terrestrial life, including an amniotic egg (with a unique set of membranes—the amnion, chorion, and allantois), a water-repellant epidermis (with epidermal scales, hair, or feathers), and, in males, a penis that allows internal fertilization.
Biota
All of the organisms—animals, plants, fungi, and microorganisms—found in a given area. (Contrast with flora, fauna.)
Cambrian Explosion
Cambrian Explosion The rapid diversification of multicellular life that took place during the Cambrian period.
Continental Drift
The gradual movements of the world’s continents that have occurred over billions of years.
Fauna
All the animals found in a given area. (Contrast with flora.)
Flora
All of the plant found in a given area. (Contrast with fauna.)
Fossil
Any recognisable structure originating from an organism, or any impression from such a structure, that has been preserved over geological time.
Gondwana
The large southern land mass that existed from the Cambrian (540 mya) to the Jurassic (138 mya). Present-day remnants are South America, Africa, India, Australia, and Antarctica.
Half-life
The time required for half of a sample of a radioactive isotope to decay to its stable, nonradioactive form, or for a drug or other substance to reach half its initial dosage.
Laurasia
The northernmost of the two large continents produced by the breakup of Pangaea.
Mass Extinction
A period of evolutionary history during which rates of extinction are much higher than during intervening times.
Pangaea
The single land mass formed when all the continents came together in the Permian period.
Plate Tectonics
The scientific study of the structure and movements of Earth’s lithospheric plates, which are the cause of continental drift.
Sedimentary Rock
Rock formed by the accumulation of sediment grains on the bottom of a body of water.
Stratum
A layer of sedimentary rock laid down at a particular time in the past.
