Chapter 19 the history of life

Chapter 19 the history of life

Paleontologists
Scientists who study fossils
Extinct
No living members
Relative dating
A method of determining the age of a fossil by comparing its placement with that of fossils in other rock layers
Index fossils
A distinctive fossil that is used to establish and compare the relative ages of rock layers and the fossils they contain
T or F: relative dating does tell the age of a fossil in years
False
Radiometric dating
Method in which scientists use radioactive isotopes to find the age of rocks and fossils.
Half-life
The time it takes for half the radioactive atoms in a sample to decay
Geologic time scale
The time line used to represent Earth’s history
T or F: the geological time scale is based on both relative and absolute dating.
True
Era
A major division of geologic time; usually divided inti two or more periods
Period
A division of geologic time into which eras are subdivided.
Which eon are humans present in the geologic time scale?
Phanerozoic
In the geologic time scale, which era are humans in?
Cenozoic
Macroevolutionary patterns
The changes in anatomy, phylogeny, behavior, and ecology, which take place in clades that are larger than a single species.
Background extinction
Extinction caused by the slow and steady process of natural selection
Mass extinction
An event during which many species become extinct during a relative short time
What process influence whether species and clades survive or become extinct?
If the rate of speciation in a clade is equal or greater than the rate of extinction, the clade will live; if the rate of extinction is greater than the rate of speciation, the clade will become extinct.
Gradualism
The evolution of species by the gradual addition of small genetic changes over long periods of time
Punctuated equilibrium
The pattern of evolution in which long stable periods are interrupted by brief periods of more rapid change
Adaptive radiation
Process by which a single species or. Small group of species evolves into several different forms that live in different ways
How fast does evolution take place
Evolution has moved at different rates for different organisms at different times over the long history of life on Earth.
Convergent evolution
Process by which unrelated organisms independently evolve similarities when adapting to similar environments
Coevolution
The process by which two species evolve in response to changes in each other over time.
What are two forms of macroevolution
Adaptive and convergent evolution
What do scientists hypothesize about early Earth?
Earth’s atmosphere was mainly CO2, water vapor, and nitrogen, with lesser amount of carbon monoxide, hydrogen sulfide, and hydrogen cyanide. It contained little or no oxygen.
What do scientists hypothesize about the origin of life?
Scientists suggested how mixtures of organic compounds necessary for life could have arisen form simpler compounds in the atmosphere of early Earth
What do fossils reveal about ancient life?
The fossil record shows the structure of ancient organisms, their environment, and the way in which they lived.
Plate tectonicts
The theory that explains the slow movement if solid continental plates over Earth’s mantle.
What three periods are in the era cenozoic?
Quaternary, Neogene, Paleogene
What do fossils reveal about ancient life?
From the fossil record, paleontologists learn about the structure of ancient organisms, their environment, and the ways in which they lived.