Download Slide 3- We are now in the Cenozoic Era (as of 65 million years ago)

Ch 17. Lecture Extra Info
Slide 3- We are now in the Cenozoic Era (as of 65 million years ago), Quaternary Period (and will be until the
next mass extinction)
History of Life on Earth: The Earth is a little over 4.5 billion years old, its oldest materials being 4.3 billionyear-old zircon crystals. Its earliest times were geologically violent, and it suffered constant bombardment from
meteorites. When this ended, the Earth cooled and its surface solidified to a crust - the first solid rocks. There
were no continents as yet, just a global ocean peppered with small islands. Erosion, sedimentation and volcanic
activity - possibly assisted by more meteor impacts - eventually created small proto-continents which grew until
they reached roughly their current size 2.5 billion years ago. The continents have since repeatedly collided and
been torn apart, so maps of Earth in the distant past are quite different to today's.
The history of life on Earth began about 3.8 billion years ago, initially with single-celled prokaryotic cells, such
as bacteria. Multicellular life evolved over a billion years later and it's only in the last 570 million years that the
kind of life forms we are familiar with began to evolve, starting with arthropods, followed by fish 530 million
years ago (Ma), land plants 475Ma and forests 385Ma. Mammals didn't evolve until 200Ma and our own
species, Homo sapiens, only 200,000 years ago. So humans have been around for a mere 0.004% of the Earth's
history.
Geological timeline
During its dramatic 4.5 billion year history, Earth has gone through a series of major geological and biological
changes. The timescale below highlights a number of notable prehistoric events and the geological periods in
which they occurred. As things didn't get interesting from a biological perspective until around 570 million
years ago, we've included a couple of zoomed in timelines to show the detail of more recent evolutionary
history.
The origin of the Earth
4.6 billion years ago
First life arises
3.8 billion years ago
Eukaryotes evolved
2.1 billion years ago
First sexually reproducing organisms
1.1 billion years ago
570 million years ago First arthropods evolve
530 million years ago The first fish
475 million years ago First land plants
385 million years ago First forests
370 million years ago The first amphibians
320 million years ago The earliest reptiles
225 million years ago The dinosaurs evolve
200 million years ago The mammals evolve
150 million years ago First birds
130 million years ago Flowering plants evolve
100 million years ago The first bees evolve
Dinosaurs and ammonites become extinct
65 million years ago
The first great apes appear
14 million years ago
2.5 million years ago Genus Homo evolves
200 thousand years ago Our species, Homo sapiens evolves
10 thousand years ago End of the last Ice Age
http://www.bbc.co.uk/nature/history_of_the_earth
Slide 4- Read attached article
Slide 6- Lamarck noted how well-adapted organisms were to their environments, and believed that fossils could
be understood as less perfect forms which had perished in the struggle for increasing perfection. He explained
adaptation as a result of change caused by environmental pressures.
Slide 7- What did Darwin say?
What evidence supports Evolution by Natural Selection?
What impact did Evolution have on biology?
Slide 8- After graduation Darwin was recommended to be the conversation companion to Captain Robert
FitzRoy, preparing the survey ship Beagle for a voyage around the world.
FitzRoy chose Darwin because of his education, his similar social class, and similar age as the captain.
Darwin noted that the plants and animals of South America were very distinct from those of Europe
Slide 9- The origin of the fauna of the Galapagos, 900 km west of the South American coast, especially puzzled
Darwin.
On further study after his voyage, Darwin noted that while most of the animal species on the Galapagos lived
nowhere else, they resembled species living on the South American mainland.
It seemed that the islands had been colonized by plants and animals from the mainland that had then diversified
on the different islands