Fossils Biology 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
Speciation development of two or more species from a single species Species A Species B Species C Species D Ancestral Species
Speciation Activity 3
Types of Speciation Allopatric - geographical separation Sympatric - occurs in same geographical area (hybrids, polyploids)
Isolating Mechanisms Spatial Temporal Behavioral Mechanical Zygote Mortality Hybrid Sterility Hybrid Reduced Fitness
Fossil remains or traces of ancient living organisms evidence for evolution show pattern of evolution can be dated
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
Activity - Relative Age Slate Shale/Siltstone Limestone Sandstone Basalt Pegmatite Granite Oldest Shale/siltstone Basalt Limestone Sandstone Pegmatite Slate Granite
Radiometric Dating Isotopes - atoms of same element with different atomic weights e.g. U-235 and U-238 92 protons, 143 vs 146 neutrons U-235 unstable U-235 Pb-207
Half-Life Time for 1/2 the isotope atoms to decay U-235 Pb-207 704 million years 100% U-235 50% U-235, 50% Pb-237
Uranium Decay half life time (millions) % of U-235 0 0 100 1 704 50 2 1408 25 3 2112 12.5 4 2816 6.25 5 3520 3.125 6 4224 1.5625
Graph of Uranium Decay 100 90 Percent uranium Remaining 80 70 60 50 40 30 20 10 0 0 1000 2000 3000 4000 5000 Million Years
Log Graph of Uranium Decay 100 Percent uranium Remaining 10 1 0 1000 2000 3000 4000 5000 Million Years
Graph of Uranium Decay 100 Percent uranium Remaining 10 0 500 1000 1500 2000 2500 Million Years
How Old is Pegmatite? U-235:Pb-207 1:1 50% U-235 : 50% Pb-207 100 Do others! Percent uranium Remaining 700 million 10 0 500 1000 1500 2000 2500 Million Years
Ages of Layers Siltstone - 70 Basalt - 380 Pegmatite - 700 Granite - 1400 Percent uranium Remaining 100 10 0 500 1000 1500 2000 2500 Million Years
Rock Age Slate Shale/Siltstone Limestone Sandstone Basalt Pegmatite Granite Oldest Shale/siltstone 70 Basalt Limestone Sandstone Pegmatite Slate Granite 380 704 1408 Why not date other layers?
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
Dating Fossils Rock Age Slate Shale/Siltstone Limestone Sandstone Basalt Pegmatite Granite Oldest Shale/siltstone 70 Basalt Limestone Sandstone Pegmatite Slate Granite 380 704 1408 Fossil bacteria and archaea are in slate Fossil trilobites in limestone fossil cycads in shale and siltstone 704-1408 380-704 70
Geological Eras Precambrian (4600-600 mya) Cambian Explosion Paleozoic (600-250 mya) Mesozoic (250-65 mya) Permian Extinction Cenozoic (65 mya - present) Cretaceous Extinction
Precambrian: 4600-600 mya 4600 mya - earth forms 3500 mya - 1st prokaryotes fossils 2100 mya - 1st eukaryotes 1000 mya - 1st multicellular
Early Earth hot atmosphere mostly H2O, N2, CO2 trace H2, CH4, NH3 Oceans form as earth cools
Miller s Experiment 1953 Spark Early Atmospheric Gases Small Organic Molecules sugar, amino acids, fatty acids
Evolution of 1st Cells Monomers Polymers Protocell amino acids nucleotides fatty acids Protein RNA, DNA lipids lipids around polymer True Cell (Replicate)
Stromatolites (early fossils - blue-green bacteria) http://en.wikipedia.org/wiki/ File:Stromatolites_in_Sharkbay.jpg
Paleozoic Era - 600-225 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%
Periods Subdivisions of Eras Permian (299-251) Carboniferous (359-299) Paleozoic Era Devonian (416-359) Silurian (444-416) Ordovician (488-444) Cambrian (542-488)
Mesozoic Era - 225-65 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 145-65 Jurassic 145-200 Triassic 200-251
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)