Evolution & Prehistoric Oceans Flashcards
Biological Evolution
The change in a population’s genetic makeup through successive generations
Microevolution
Describes the small genetic changes that occur in a population
Macroevolution
Describes long-term, large-scale evolutionary changes among groups of species
Natural Selection
Concept was introduced by Charles Darwin in 1846
This process occurs when some individuals of a population have genetically based traits that cause them to better survive and produce offspring (called an adaptive trait, or adaptation)
Paleontologist
Study fossils to learn about the Earth’s history
Trace Fossils
Footprints, buttows, etc.
Index Fossils
Found exclusively in rock layers of a particular geological age
Transitional Forms
Many are educational guesses as to what the organisms looked like as they evolved
Extinction
When environmental conditions change, a species may either evolve or become extinct
Background Extinction
Species disappear at a slow rate
Mass Extinction
An abrupt rise in extinction rates
Precambrian Era (4.6 BYA - 570 MYA)
4.6 BYA-
The Earth was formed
Early atmosphere was water vapor, carbon dioxide, and nitrogen
4.2 BYA-
Ocean formed as the planet cooled, water vapor condensed
3.6 BYA-
The first evidence of life, cyanobacteria
2.5 BYA-
Oxygen begins to accumulate in the atmosphere
Paleozoic Era (570 MYA - 248 MYA)
490 MYA-
Brachiopods, cephalopods, and trilobites dominate
443 MYA-354 MYA-
The Devonian Period is known as the “Age of Fishes”
250 MYA-
Large scale climatic changes led to the Permian extinction wiping out 90% of marine species
Mesozoic Era (248 MYA - 65 MYA)
200 MYA-
Pangea breaks up and continents begin to move to their current locations
Cenozoic Era (65 MYA - Present)
Known as the “Age of Mammals” with mammals replacing reptiles as the dominant land animals
Diversity continues to increase in the oceans
