Chapter 3 Geological History Flashcards
3.9-2.5 BYA
Evidence lost due to remelting of old rock and formation of new.
Marked by presence of oldest known rocks
Meteors hitting earth
Earliest evidence of life is bacteria and blue-green algae from 3.5 BYA
Stromatolites
M
Archean Eon
4.6-3.9 billion years ago
Earth was hot consisting of molten rock and water in gaseous state.
No evidence of life
Hadean Eon
2.5-0.6 BYA 1-2 continents Seas becoming salty from land runoff Oxygen accumulates in sea and atmosphere Atmospheric shield begins to protect from UV rays Continuation of prokaryotes 1st eukaryotes 2.1 BYA New life forms arose in shallow seas Segmented worms, Arthropods, algae.
Proterozoic Eon
590 MYA to present day
Divided into 3 eras.
Super continent Pangea, continents break up.
Periods of hot and cold (glaciation)
Shallow seas drying up and inundating land.
Explosion of diversity in life forms
Several extinction events followed by new species.
Phanerozoic Eon
590-248 MYA
Most continents joined, some northern continents separate.
All-time low regression of sea.
Cambrian explosion of new life forms.
1st vertebrate, fish, amphibian, reptile.
1st insects after time.
Ends with the greatest extinction event ever!!!
Paleozoic Era
Up to 96% of all marine species went extinct. 70% of terrestrial vertebrates went extinct.
Mass extinction of insects.
Cause of extinction event is unknown. (volcano, bolide impact, sea level change, methane release)
Permian Triassic extinction event
248-65 MYA
Age of reptiles. Subdivided periods: Triassic, Jurassic, Cretaceous.
Begins with one Pangea and one Pathallasa
Early Jurassic, northern continents separate off as Laurasia.
Southern continents stay together as Gondwanaland.
Warm climate mostly.
1st mammals early, 1st dinosaurs rule most of the time,
1st birds and first flowering plants. Much diversity
Ends with the 2nd greatest extinction event ever. K-T boundary
All large dinosaurs and vertebrates went extinct.
Mammals, fish, land plants mostly survived
Cause = bolide impact
Mesozoic Era
65 MYA to present day “age of mammals”
Continents move to current locations
Adaptive radiation and evolution of current biota
Cenozoic Era
(2MYA - 10,000 YA) Significant cooling and glaciations
Pleistocene Epoch
70 MYA made for the first time connecting Alaska and Siberia.
3-6 MYA marine corridor runs through.
Ice ages change sea level and bridge re-submerges multiple times
Beringia
Direct effects of glaciation:
Totally covered and scoured some parts of northern hemisphere.
Dumped glacial debris
Force biota to move south some later return after warming
Scoured out valleys
Rerouted rivers
Dammed or created lakes
Sea levels fell by as much as 100m
Land bridges formed such as Beringia
Affected climate worldwide, generally drier and cooler in tropics.
Causes to Pleistocene glaciations due to changes in earths orbit, thus changes in the amount of solar radiation received.
Milankovich Cycles
Variation in ellipticity of the Earth’s orbit.
Eccentricity
Biota responses for survival:
Move
Adapt
Die
A single evolutionary line. (George Simpson)
Evolutionary Species Concept
A group of species with the same type of morphological characteristics.
“Type Specimen” - identified and described and recognized by similarity to the type specimen.
Typological Species Concept
Groups of interbreeding natural populations that are reproductively isolated from other such groups (Mayr)
Group of organisms that can interbreed naturally and produce fertile offspring.
Biological Species Concept
Like biological concept but also…. a group of organisms that can interbreed and produce fertile offspring AND produce offspring at least as fertile and adaptive as the parent strains.
-not applicable for asexual reproduction.
Ecological Species Concept
The functional unit of heredity, a discrete piece of DNA that contains info affecting one or more trace.
Gene