1. When Did we start thinking the EARTH is OLD?
Darwin argued that earth could be billions of years old
Small geological formations estimated to bee 300 million years old, based on observations of erosion.
Kelvin estimated 20 million years based on cooling of the Earth.
Scientists were debating between millions and billions, not billions and thousands!

2. Radiometric dating indicates that the earth is 4.6 billion years old

3. Fossils allow us to learn about extinct species
Morphology
Behavior
Development

4. Most organisms don’t fossilize

5. Occasionally soft tissues fossilize
Burgess shale
505 million years ago
~65,000 specimens
~93 species

6. Burgess Shale Discovered in 1909 by Charles Walcott
Yoho National Park, British Columbia
Made famous by Stephen J. Gould’s 1989 book: Wonderful Life
Records fossil life after the Cambrian explosion

7. CAMBRIAN EXPLOSION 542 million years ago
time at which most animal phyla first appear in the fossil record
appears sudden in the fossil record

8. Burgess Shale: Gould
Burgess shale life forms include things similar to contemporary animals and things not at all found in contemporary life
Non-extant forms appear just as well adapted to Cambrian life as those forms that survived
A new Burgess shale formation was found in 2013: 50 additional species

9. Fossils provide clues about behavior

10. Fossils provide clues about development

11. Scanning electron microscopy provides evidence of cellular structure
Structure of melanosomes suggests striking plumage

12. DINOSAUR Courtship? Crest connected to nasal cavity
Sound generated by blowing air
Ears tuned to this frequency
Younger animals had higher sound
Older animals had deeper further ranging sound