Fossils Biology 2 Thursday, January 31, 2013

Transcription

1 Fossils Biology 2

2 Evolution Change in the genetic composition of a group of organisms over time. Causes: Natural Selection Artificial Selection Genetic Engineering Genetic Drift Hybridization Mutation

3 Speciation development of two or more species from a single species Species A Species B Species C Species D Ancestral Species

4 Speciation Activity 3

5 Types of Speciation Allopatric - geographical separation Sympatric - occurs in same geographical area (hybrids, polyploids)

6 Isolating Mechanisms Spatial Temporal Behavioral Mechanical Zygote Mortality Hybrid Sterility Hybrid Reduced Fitness

7 Fossil remains or traces of ancient living organisms evidence for evolution show pattern of evolution can be dated

8 Relative Dates Principle of Superposition - younger sedimentary rocks are on top of older sedimentary rocks. Principle of Cross-Cutting Relations: any geologic feature is younger than anything else it cuts across

9 Activity - Relative Age Slate Shale/Siltstone Limestone Sandstone Basalt Pegmatite Granite Oldest Shale/siltstone Basalt Limestone Sandstone Pegmatite Slate Granite

10 Radiometric Dating Isotopes - atoms of same element with different atomic weights e.g. U-235 and U protons, 143 vs 146 neutrons U-235 unstable U-235 Pb-207

11 Half-Life Time for 1/2 the isotope atoms to decay U-235 Pb million years 100% U % U-235, 50% Pb-237

12 Uranium Decay half life time (millions) % of U

13 Graph of Uranium Decay Percent uranium Remaining Million Years

14 Log Graph of Uranium Decay 100 Percent uranium Remaining Million Years

15 Graph of Uranium Decay 100 Percent uranium Remaining Million Years

16 How Old is Pegmatite? U-235:Pb-207 1:1 50% U-235 : 50% Pb Do others! Percent uranium Remaining 700 million Million Years

17 Ages of Layers Siltstone - 70 Basalt Pegmatite Granite Percent uranium Remaining Million Years

18 Rock Age Slate Shale/Siltstone Limestone Sandstone Basalt Pegmatite Granite Oldest Shale/siltstone 70 Basalt Limestone Sandstone Pegmatite Slate Granite Why not date other layers?

19 Types of Rock Igneous - formed by melting e.g. granite, basalt Best for dating - melting resets clock (lead is lost) Sedimentary - formed by weathering and deposition of particles from parent rock, e.g. sandstone, limestone Dating indicates age of parent rock, not rock layer itself Metamorphic - from recrystallization or other rock due to high temperature and pressure e.g. marble and slate

20 Dating Fossils Rock Age Slate Shale/Siltstone Limestone Sandstone Basalt Pegmatite Granite Oldest Shale/siltstone 70 Basalt Limestone Sandstone Pegmatite Slate Granite Fossil bacteria and archaea are in slate Fossil trilobites in limestone fossil cycads in shale and siltstone

21 Geological Eras Precambrian ( mya) Cambian Explosion Paleozoic ( mya) Mesozoic ( mya) Permian Extinction Cenozoic (65 mya - present) Cretaceous Extinction

22 Precambrian: mya 4600 mya - earth forms 3500 mya - 1st prokaryotes fossils 2100 mya - 1st eukaryotes 1000 mya - 1st multicellular

23 Early Earth hot atmosphere mostly H2O, N2, CO2 trace H2, CH4, NH3 Oceans form as earth cools

24 Miller s Experiment 1953 Spark Early Atmospheric Gases Small Organic Molecules sugar, amino acids, fatty acids

25 Evolution of 1st Cells Monomers Polymers Protocell amino acids nucleotides fatty acids Protein RNA, DNA lipids lipids around polymer True Cell (Replicate)

26 Stromatolites (early fossils - blue-green bacteria) File:Stromatolites_in_Sharkbay.jpg

27 Paleozoic Era mya Cambrian Explosion Invertebrate animals e.g. trilobites. 1st Vertebrates - fish, salamanders, reptiles Algae Lichens - 1st land plant-like 1st Mosses 1st Ferns 1st Seed Plants Permian extinction 95%

28 Periods Subdivisions of Eras Permian ( ) Carboniferous ( ) Paleozoic Era Devonian ( ) Silurian ( ) Ordovician ( ) Cambrian ( )

29 Mesozoic Era mya Age of the Reptiles Ferns common - some tree size. Seed ferns - extinct intermediate between non-seed and seed plants. 1st Flowering plants 1st Birds and Mammals Great Cretaceous Extinction (76% species) Periods Cretaceous Jurassic Triassic

30 Cenozoic Era - 65 mya - present Insects and mammalsdominant land animals Flowering plants - dominant land plants. Algae-dominate sea Great Quaternary Extinction? Periods Quaternary (1.8-0) Tertiary (65-1.8)