chapter 22 Flashcards
History of life on Earth
What are the preserved remains of the past life ?
Fossils
What does the oldest fossil resemble ? How old
Cyanobacteria and 3.5 billion
Radiometric dating
a method
of dating samples by
determining the relative
proportions of particular
radioactive isotopes present in
the sample
The major environmental changes that could cause extinction
Temperature (Ice Age, tropic vs arctic)
* Composition of atmosphere (O2)
* Shifting of landmasses (continental drift)
* Floods and glaciations
* Volcanic eruptions
* Meteorite impacts
When did Prokaryotic cells arise ?
Archaean Eon
When was the formation of the earth
500 years ago and earth was too hot
When did microbial life flourish in the primordial ocean /
Archean
During the archaeon eon all the life forms were..
Prokaryotic and anaerobic
Heterotrophs
derive their energy from the chemical bonds within
the organic molecules they consume
Autotrophs
directly harness energy
from either light or inorganic molecules
What was the first form of life
Unsure
What year does multicellular eukaryotes emerge
1.5 billion years ago
What was the oldest fossil preserved
Autotrophic Cyanobacteria
Cyanobacteria formed in layers is called
Stromatolites
When did Eukaryotic cells arise ?
PROTEROZOIC EON
Where is it thought of simple multicellular emerged
Aggregation process and by cell divsion and adhesion
How does aggregation occur ?
When individual cells find each other and form a colony.
Example: Slime modes
What were the first animals
Invertebrates (580-600 mya)
When did the phanerozoic eon start ?
543 mya
The 3 periods of the Phanerozoic eon
Paleozoic,Mesozoic, Cenozoic
Most animals exhibit
bilateral symmetry
The paleozoc era covers
300 million years
The 6 periods of the Paleozoic era
Cambrian, Ordovician, Silurian, Devonian, Carboniferous,
and Permian
What did the Cambrian period cover
(543-490 Mya)
-Rapid incensement in animal diversity
Ordovician Period
(490-443 Mya)
- Climate is warmer
- Marine communities evolved
- Early land plants and arthropods have landed ( maybe)
- Large glaciers were formed,
Phanerozoic Eon saw the
Diversification
of Invertebrates & Colonization of Land by Plants & Animals
Silurian Period
(443-417 mya )
- no major types of invertebrates but changes
- Major colonization of land by terrestrial plants and animals
-Earliest vascular plants arose
Devonian Period
(417-354 mya)
- Major increase in the number of terrestrial plant species; ferns, horsetails, and seed plants (gymnosperms) emerge
- Insects emerge
* Tetrapods (amphibians) emerge
* Invertebrates flourished in oceans
* Near the end of the period, a
prolonged series of extinctions
eliminated many marine species
Carboniferous Period
- A cooler period where much land was covered by forest
swamps; coal formed over millions of years from compressed
layers of rotting vegetation - first flying insects
- Amniotic egg emerges, which
was a critical innovation for the
emergence of reptiles
Permian Period
(290-248 mya)
- The largest known mass extinction occurred ( the end )
Triassic Period
( 248-206 mya )
- Reptiles were plentiful and new groups arose (crocodiles,
turtles)
* First dinosaurs (a diverse group of reptiles) emerged during the
middle of the Triassic
* First mammals emerged
The 3 Mesozoic periods
Triassic. Jurassic and cretaceous
Jurassic Period
(206- 144 mya )
Gymnosperms (ex: conifers) continued to be dominant
vegetation; dinosaurs and other reptiles continued to be
dominant land vertebrate
Cretaceous Period
(144-65 mya)
-Dinosaurs continued to be dominant land animals
The 2 years of the Cenozoic era (65 million years)
Tertiary and Quaternary
We are currently in the..
Quaternary Period
Tertiary Period (65-1.8 mya) is when
Mammals that survived the Cretaceous began to rapidly
diversify during the early Tertiary
* Angiosperms became dominant land plants;
When did Homo sapiens appear ?
200,000 years ago
When did hominoids emerge ?
7 mya
