The Study of Fossils Is Called. Paleontology
Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.
1. The Fossil Record
2. The Study of Fossils Is Called Paleontology
“Words about Ancient Life”
3. Fossils Give the best direct evidence of evolution
5. Types of Fossilization
6. Molds Impression of an organism after original material disappears
7. Casts Molds that are filled in with other materials
8. Tracks & Burrows Indicative structures: (Indicate presence), e.g.
Worm burrows -------------->
9. Replacement Original material is replaced by other stuff
10. Petrified wood www.petrifiedforest.org
11. Sometimes... Original parts are preserved Unusual environmental conditions
Example: 30 million year old wasps in amber
13. And, Finally ...
14. Coprolites Er, um,... there’s no nice way to say it,
... they’re fossilized POOP !
Indicate dietary components
15. Fact: Hard parts (like shells, bones, teeth) are NOT needed for fossilization
E.g., this fossil fern --------------------->>>>
However, hard parts are more readily preserved
16. The Extent of Geologic Time
17. Just after midnight ... About 4.5 billion years before present (YBP)
Earth is still forming: “final accretion”
18. 2:45 - 3:50 AM About 4.0 - 3.8 billion YBP
19. 9 PM About 570 million YBP
Time before this is called
20. 11 - 11:40 PM 200 - 65 million YBP
Dr. Brodman’s lecture next Wednesday
21. 11:59:58 PM 120,000 (?) YBP
Modern humans appear
22. Some Complications
23. Plate Tectonics Active throughout Earth’s history
Movement of plates caused mountain building and
The crushing and melting have destroyed many fossils over time
24. Conditions Must be “just right” for fossilization
25. Conditions... Quick burial & hard parts are best
That’s why there are more marine fossils than any other
Most of ancient life never had a chance to become fossils
Text: Only 1 out of 10,000 species got preserved!
26. The Atmosphere Original atmosphere had little or no free oxygen (O2)
Evidence of evolution of the atmosphere includes:
27. Stromatolites One of oldest fossils
Mixture of green bacteria and minerals
Bacteria were photosynthetic - made O2
This picture is of a modern form found in Australia ------> >
28. 1.6 Billion year old fossil version
29. Very old: 1.8 - 3.0 By
Evidence that O2 was forming in oceans
BIF isn’t forming today - too much O2 in atmosphere BIF
30. Red Beds Indicate abundance of O2 in atmosphere
1.0 - 2.0 billion ybp
31. Land Organisms Must have protection from Sun’s UV radiation
First land plants and animals appeared around 400 million YBP
So, must have had OZONE layer (O3) in stratosphere by then
32. Free Oxygen - O2 Contemporary organisms could not have evolved without lots of O2
33. The Cambrian Explosion 570 - 500 Million YBP
34. Before 800 million YBP... There were only single-cell life forms
Bacteria & Protista
Soft-bodied metazoans, or multi-cellular animals (think of a jellyfish) appear in the fossil record about 800 million YBP
May have existed as far back as 900Mybp, but no hard parts
Only seen as trace fossils
Contemporary organisms could not have evolved without lots of O2
35. Late Precambrian Metazoans Looks like modern Jellyfish, worms, sea pens
“Vendian” period: 700-570 mybp
36. Cambrian “explosion” Cambrian “explosion” of life followed high free O2 level
Began age of abundant life
This explosion of life was also aided by ...
37. SEX !
38. One of the best Cambrian fossil formations is the Burgess Shale in the Canadian Rockies of British Columbia
39. Burgess Shale Facts
40. Burgess Shale Facts Declared a World Heritage site by the United Nations in 1981 (582 total sites) Taj Mahal, Great Wall, Tower of London, Galapagos, etc...
According Stephen Jay Gould, these fossils "deserve to be as prominent in the public consciousness as Big Bangs & Black Holes"
41. Burgess Facts Rock formed in a shallow marine environment 540 mybp
But are now about 9,000 feet (almost 2 miles) above sea level
What’s this tell you about earth history?
42. Burgess Shale Lifeforms soft-bodied preservation of a wide diversity of fossil invertebrate animals
At least 5 of the modern phyla of animals existed, including chordates, the same phylum as humans
44. Hallucigenia Worm-like with spikes
Not sure which is head and which is tail
45. we must mention Trilobites Over 600 species in the Cambrian
So common that they are index fossils of that period
46. Overall, There was a great diversity of life in the Cambrian, perhaps more than today...
But, most of the strange forms became extinct
Supports S.J. Gould’s “punctuated equilibrium” idea
47. Eras of “Abundant Life” “Prime Time”
From oldest to youngest:
48. PALEOZOIC 570 - 230 million YBP
Age of Invertebrates and (a bit later), fish
49. The Paleozoic Ended with a mass extinction
90 - 95% of all marine species became extinct!
No one knows for sure why
Global cooling, reduced shallow water areas, etc...?
50. MESOZOIC 230 - 65 million YBP
Age of Reptiles, also small mammals
51. The Mesozoic Also ended with a mass extinction
Perhaps 75% of all life on Earth
End of the dinosaurs (at least the big ones!)
52. CENOZOIC From Mesozoic extinction ==> present
Age of Mammals (us!)
53. That another mass extinction is progress now!
Caused by human interaction with the environment
Wiping out tropical rainforests and other wildlife habitats… done Some scientists believe