Ch. 23.1 Broad Pattern of Evolution

Question 1

Macroevolution

Answer 1

The broad pattern of evolution above the species level, ie. the emergence of terrestrial vertebrates through a series of speciation events, the impact of mass extinctions on the diversity of life, and the origin of key adaptations such as flight in birds.

Question 2

Radiometric Dating

Answer 2

A way in determining the age of a fossil which is based on the decay of radioactive isotopes. In this process, a radioactive “parent” isotope decays to a “daughter” isotope at a characteristic rate. the rate of decay i expressed by the half-life.

Question 3

Half Life

Answer 3

The time required for 50% of the parent isotope to decay. Each type of radioactive isotope is not affected by temperature, pressure or other environmental variables.

Question 4

Geologic Record

Answer 4

A standard time scale that divides Earth’s history into four eons and further subdivisions.

Question 5

Stromatolites

Answer 5

Layered rocks that form when certain prokaryotes bind thin films of sediment together. These and other early prokaryotes were Earth’s sole inhabitants for about 1.5 billion years. Early prokaryotes included cyanobacteria and other photosynthetic species that transformed life on our planet by releasing oxygen to the atmosphere during the water-splitting step of photosynthesis.