Class Notes (1,100,000)
US (460,000)
UC-Irvine (10,000)
BIO SCI (2,000)
Lecture 9

BIO SCI 94 Lecture Notes - Lecture 9: Phanerozoic, Adaptive Radiation, MesozoicPremium


Department
Biological Sciences
Course Code
BIO SCI 94
Professor
Brad Hughes
Lecture
9

This preview shows page 1. to view the full 4 pages of the document.
1/25/19
Life’s Timeline
Best estimate:
Earth formed 4.6 billion years ago
Life began 3.4 billion years ago
Researchers
Earth’s history divided into eons, eras, and periods
Precambrian
Precambrian-Earth’s formation to start of most animals groups 542 millions years
ago
Divided into Hadean, Archaean, and Proterozoic eons
In the Precambrian
Life exclusively unicellular
No oxygen in ocean and atmosphere until birth of photosynthetic bacteria
Phanerozoic Eon
The Phanerozoic eon
542 millions years ago to present
Threes eras- Paleozoic, Mesozoic, Canezoic
Paleozoic Era
The origin and beginning diversification of animals, plant life, and fungi
Land animals appear
At the end of Permian period, nearly all multicellular life-forms die
Mesozoic Era
Most dominant terrestrial plants-gymnosperms
Most dominant terrestrial vertebrates-dinosaurs
Cenozoic Era
Most dominant terrestrial plants-angiosperms
Largest terrestrial vertebrates-mammals
Adaptive Radiation
Adaptive radiation- from single lineage, rapid production of many descendent
species
Wide range of adaptive forms
30 species of Hawaiian silverswords have traits of adaptive radiation:
Monophyletic group
Speciated rapidly
Diversified ecologically
Niche-range of resources available to species and tolerable conditions
Why Do Adaptive Radiations Occur?
Two ways to trigger adaptive radiations:
New Resources
You're Reading a Preview

Unlock to view full version

Subscribers Only