Chapter 12 Vocab Flashcards
Radiometric dating
Tequnique that uses the natural decay rate of isotopes to calculate the age of material
Relative dating
Estimate age of a fossil based on the location of fossils in strata
Isotopes
Atoms of an element that have the same number of protons but a different number of neutrons
Half life
Amount of time it takes for half of the isotope in a sample number of protons to decay into its product isotope
Index fossils
Existed only during specific spans of time over large geographic areas
Geologic time scale
Time scale representing the history of earth
Era
Lasts tens to hundred of millions of years and consisting of two or more periods, second largest unit of geologic time
Periods
Most of commonly used units of time on the geologic time scale, lasts tens of millions of years and is associated with a particular type of rock system
Epoch
Smallest unit of geologic time, lasts several million years
Nebula
Rotating cloud of gas and dust
Ribozymes
RNA molecule that can catalyze specific chemical reactions
Cyanobacteria
Bacteria that can carry out photosynthesis
Endosymbiosis
Ecological relationship in which members of every major animal group alive today evolved
Paleozoic
Era of geologic time during which members of every major animal group alive today evolved
Cambrian explosion
Earliest part of the Paleozoic era, when a huge diversity of animal species evolved
Mesozoic
Era during which dinosaurs romed earth
Cenozoic
Geologic time period that began 65 million years ago and continues today
Primates
Mammal with flexible hands and feet, forward-looking eyes, and enlarged brains relative to body size
Prosimians
Oldest primate group that includes mostly small, noctural primates
Anthropoids
Humanlike primate
Hominids
Primate that walks upright, has long lower limbs, oppose able thumbs and other four fingers, and a relatively large brain
Bipedal
Animal that walks on two legs
