1. Intro to Evolution Evolution simply means change over time.
many things evolve, including languages, and your view of the world.

2. Intro to Evolution This unit is meant to introduce you to:
the development of current evolutionary theory and subtopics
processes which influence the change of species over time
This unit is not meant to:
tell you what you have to believe

3. Intro to Evolution
This unit is a spectacular view into what science truly is:
we are constantly learning new things on our own and from others
making mistakes and learning from them
making revisions based on new data
improving on techniques that work or don’t work at all.
taking data and attempting to determine its meaning
figuring out the “how” of things

4. Timeline, Fossils & Dating Methods
Unit 5 – Lecture 1

5. Evolutionary Timeline
The evolutionary timeline is divided into sections of time called eras – which are then divided into smaller units of time called periods.
units of time are determined through use of radiometric dating methods, fossil/rock identification, and geographic strata [rock layers].
evolutionists estimate the age of the earth to be approximately 4.5 billion years old

6. Evol. Timeline – cont’d Hadean: 3.8-4.5 billion years ago
think “Hades”
very hot
very little free oxygen,
lots of CO2
lots of N2 [nitrogen] gas
lots of water vapor

7. Evol. Timeline – cont’d
Precambrian [anything from hadean to cambrian…]
cyanobacteria and other prokaryotes
sponges & cnidarians [jellyfish/ anemone]

8. Evol. Timeline – cont’d Paleozoic [542 mya – 251 mya]
six periods – need to know: Cambrian [1st of six]
sudden occurrence - “explosion” of life [Cambrian Explosion] seen in fossil record
worms, sea stars, trilobites, fish, reptiles…
other chordates and hard-bodied organisms

9. Evol. Timeline – cont’d Mesozoic [251 mya – 65 mya] three periods :
Triassic – small mammals
Jurassic – dinosaurs
Cretaceous – flowering plants

10. Evol. Timeline – cont’d Cenozoic: 65.5 million years ago - present
lots of mammals

12. Continental Drift
Continental Drift Theory states that continents have moved throughout history
continents are still moving approx 6cm a year
Plate Techtonics explains HOW continents move

13. Continental Drift – cont’d
Continental Movement:
Pangaea – central land mass
Laurasia [northern continents] & Gondwana [southern continents]
end of Mesozoic = modern continents
[Triassic]

14. What is the difference between Continental Drift and Plate Tectonics?
Discuss
What is the difference between Continental Drift and Plate Tectonics?

15. Fossils most fossils are found in sedimentary rock
Fossil – evidence of an organism which lived long ago
paleontologist – scientist who studies ancient life
most fossils are found in sedimentary rock

16. Fossils – cont’d Types of Fossils:
trace fossils – animal markings [footprint, trail, burrow]

17. Fossils – cont’d Types of Fossils:
casts– mineralization of a space left by a decayed organism [most fossils you think of]
molds– empty space in rock from a decayed org.

18. Fossils – cont’d Types of Fossils:
imprints – made typically by thin objects that have been pressed into an area

19. Fossils – cont’d Types of Fossils:
carbonized – high temps & pressures expel gaseous elements leaving only carbon

20. Fossils – cont’d Types of Fossils:
petrified – entire organism is replaced by mineral matter.

21. Fossils – cont’d Types of Fossils:
ice- or amber- preserved fossils [True-Form Fossils]

22. Fossils – cont’d Types of Fossils:
permineralization – pores are filled with mineral matter without getting rid of organic [carbon] material

23. Fossils – cont’d
Types of Fossils:
coprolite – fossilized dino poop

24. Name and describe 5 types of fossils.
Discuss
Name and describe 5 types of fossils.

25. Fossils – cont’d
What do we know about this fossilized organism?

26. Fossils – cont’d Fossils CAN Tell Us…[sometimes]
what an organism looked like
what kinds of food it probably ate
exceptions…like the panda – has very sharp teeth for eating rough bamboo
what type of area it may have lived in / climate
geography of the area it lived in

27. Fossils – cont’d Fossils CAN’T Tell Us… what colors an organism was
almost anything about behavior
science does attempt some basic conclusions about organisms based on how they are found
nests [nurturing], found traditionally in large groups [may have been a pack organism], etc.
what it sounded like
we can make comparisons and guess at times based on structure similarities

28. Discuss
Discuss with a partner certain things that we can and can’t learn from fossils.

29. Dating Methods
Relative Dating – dating new samples based off of comparison to previously dated materials
uses circular reasoning:
dating rocks by their fossils
dating fossils by the rock in which they are found

30. Dating Methods – cont’d
Relative Dating [cont’d]
geologic layers as in the record are not actually found in their stated order anywhere on earth; they are approximated based on comparison of fossils and other rock
these things can lead to misinterpretation

31. Dating Methods – cont’d
Radiometric Dating – examining the chemical “half-life” of a substance in the sample to determine its approximate age

32. Dating Methods – cont’d
Radiometric Dating [cont’d]
half-life – the amount of time it takes for half of a substance to change [decay] into another substance
based on isotopes
isotope – atoms of an element with a different number of neutrons than is typical
the measured isotopes are radioactive and slowly become non-reactive [this is what is measured]

33. Dating Methods – cont’d
Radiometric Dating [cont’d]
ex: Carbon-14 dating, Potassium-Argon dating,

34. What is the difference between relative dating and radiometric dating?
Discuss
What is the difference between relative dating and radiometric dating?

35. Dating Methods – cont’d
Problems with Radiometric Dating
must know original amount of substance present to calculate time
must assume constant decay
must know no outside influence occurred [like water, extra heat or pressure, other substances which react]

36. Dating Methods – cont’d
Problems with Radiometric Dating
can’t date rocks which have been in water, but many fossils are formed in sedimentary rock
in this case, rock ages are dated by the fossils found in them that have been previously identified
recent samples showing millions of years
Mt. St. Helens – dated 10 yrs after eruption; showed almost 3 million years date
samples showing negative age

37. Discuss
What are potential problems in relative dating and in radiometric dating?

38. Science!
There are ways that ALL techniques can be refined and improved – that’s the job of science – to keep learning more and going farther with research and doing many trials [when possible] to get to the most accurate data possible.
To Know.

39. Homework
Complete the Stego/Horse worksheet you received.