Period		Animal with a backbone.
Comet		Unit of geologic time into which geologists divide eras.
Invertebrate		Collection of ice and dust that orbits the sun, typically in a long, narrow orbit.
Vertebrate		Many types of living thing become extinct at the same time.
Amphibian		Vertebrate, body temperature is regular by its internal heat it have his sking coverd with hear or fur and glands that produce milke to feed its young.
Reptile		Animal without a backbone.
Mass extinction		Vertebrate whose temperature is determined by the temperature of its environment, that has lung and scaly skin, ant lays eggs on land.
Mammal		Vertebrate whose body temperature is determining by the temperature of its environment.