Chapter 25 Flashcards
what are some examples of macroevolutionary changes over large time scales (not proven)
- emergence of terrestrial vertebrates
- impact of mass extinctions
- origin of flight in birds
fossil record reveals ….
changes in the history of life on Earth
sedimentary rocks are deposited into layers called ____
strata
—and are the richest source of fossils
few individuals have fossilized
-fossil record is biased in favor of species that…
- existed for a long time
- were abundant and widespread
- had hard parts
sedimentary strata reveal…
the relative ages of fossils
radiometric dating
The absolute ages of fossils can be determined by this
-A “parent” isotope decays to a “daughter” isotope
at a constant rate
half life
Each isotope has a known half-life, the time required for half the parent isotope to deca
radiocarbon dating can be used to date fossils up to ….
75,000 years old
cambrian explosion
refers to the sudden appearance of fossils resembling modern animal phyla in the Cambrian period (535 to 525 million years ago)
continental drift has many effects on living organisms
– A continent’s climate can change as it moves
north or south
– Separation of land masses can lead to allopatric speciation
Extinction can be caused by
changes to a species’
environment
mass extinction can _____ and _____
Mass extinction can alter ecological communities and the niches available to organisms
adaptive radiation
*what three things might it follow?
-organisms diversify rapidly into a multitude of new forms, particularly when a change in the environment makes new resources available, creates new challenges, or opens new environmental niches.
• Adaptive radiations may follow
– Mass extinctions – The evolution of novel characteristics – The colonization of new regions
