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EXAM 2 Review - EXAM 2 Review LECTURE TOPIC 4...

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EXAM 2 Review LECTURE TOPIC 4: MACROEVOLUTION (Figures 25.4-25.18, Table 25.1 required knowledge, Concept Checks 25.2-25.4, Summary of Key Concepts 25.2-25.4, Self Quiz 25-2,3,4) (CH26 all figures, concept checks, all summary of key concepts, and all self quiz questions) 1. Fossil Record and geologic time a. Sedimentary rocks are the richest source of fossils Sediment covers the carcass of the critter Water: protects from scavengers; low O2 levels might helo resist deterioration Eventually erosion exposes the sediment b. Paleontologists use a variety of methods to date fossils Explosives, brushes Compounding variable (ex. flood drowned animal) Impressions: imprint in rock Petrification: infiltrated with minerals Casts: the organism decomposed, leaving a mold filled with minerals Trace fossils: footprints, burrows, trails, scratch marks (has misled in the past) Amber: fossilized plant/tree resin (sap), can be >100 yrs old, DNA, cellular structures like muscle cells and mitochondria, green leaves Chemical fossil indicating a particular form of life Archoeopteryx: Sometimes called the first bird, but probably not the direct ancestor of birds today, brain studies indicate the bird could fly Feathers… Dinosaur- insulation, perhaps lift Birds today- flight, insulation, sexual selection Earliest birds- same function as birds today Molecular phylogenetics- trace evolutionary history of birds ? The fossil evidence that birds existed pior to 65.5 MYA was excellent and convincing Droppings, coprolite- good indicator of species in past Sedimentary rocks Sand sandstone Mud shale Limestone, marine deposits, lots of Calcium-rich shells and reef-forming critters Some critters don’t have skeletons to leave fossils- leave shells Fossilized protein from dinosaur Sounds, not completely ruled out strategy
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Index fossils (marine) something has changed, not arbitrary, associated with asteroids/meteorites; biloeds Absolute dating is not absolute Marie Curie/Madam Curie discovered radioactive decay Racimization = chemical conversion, when the organism died c. The fossil record is a substantial, albeit incomplete, chronicle of evolutionary history Fossil record can be biased: 1- In favor of organisms of species that lasted for long periods 2- In favor of very abundant organisms 3- In favor of widespread organisms 4- In favor of organisms with hard shells or bones Most fossils formed are destroyed, only a fraction preserved Fossil record only provides an outline Molecular clocks/phylogenies provide extra evidence d. Phylogeny has a biogeographical basis in a continental drift Biogeography of continental drift (glyptodonts and armadillos) Continental drift- 1960’s new data supported idea Relative positions of continents will change over time Thin Crust, moving mantle, nougat center Volcanic activity and earthquakes: where plates overlap Measured in centimeters, some plates move slow some fast, plates can crash gently move or slide into each other sideways Subduction zone : where one plate has crammed into another… volcano forms Ireland has a lot of volcanic activity, moving
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