2 17.1 The Fossil Record Paleontologist: scientist who studies fossils Fossil: preserved remains or evidence of an ancient organismExtinct: term used to refer to a species that has died outKey Concept: The fossil record provides evidence about the history of life on Earth. It also shows how different groups of organisms, including species, have changed over time.
3 17.1 Interpreting Fossil Evidence Relative dating: age of a fossil is determined by comparing its placement with that of fossils in other layers of rockIndex Fossils: distinct fossils found in certain layers of rock in a wide geographic range (Fig. 17-3)Key Concept: Relative dating allows paleontologists to estimate a fossil’s age compared with that of other fossils.
4 17-1 Radioactive DatingScientists use half-lives of radioactive elements to determine the age of a sample.Half-life: length of time required for half of the radioactive atoms in a sample to decay (Fig. 17-4)Key Concept: In radioactive dating, scientists calculate the age of a sample based on the amount of remaining radioactive isotopes it contains
6 17.2 Formation of EarthEstimated age of the earth based on geological evidence: 4.6 billion yearsKey Concept: Earth’s early atmosphere probably contained hydrogen cyanide, carbon dioxide, carbon monoxide, nitrogen, hydrogen sulfide, and water.
7 17.2 The First Organic Molecules Two scientists created conditions of the early Earth in the lab. After a few days, several amino acids formed. (Fig. 17-8)Key Concept: Miller and Urey’s experiments suggested how mixtures of the organic compounds necessary for life could have arisen from simpler compounds present on a primitive Earth.“Scientists now know that Miller and Urey’s original simulations of Earth’s early atmosphere were not accurate.” (p. 424)
8 17.2 Free OxygenEarly life forms were anaerobic because they lived in an oxygen-free environment.Key Concept: The rise of oxygen in the atmosphere drove some life-forms to extinction, while other life-forms evolved new, more efficient metabolic pathways that used oxygen for respiration.
9 17.2 Origin of Eukaryotic Cells Endosymbiotic theory: eukaryotes formed from the symbiotic (interdependent) relationship between ancestral eukaryotes and aerobic or photosynthetic bacteria. (Fig )Key Concept: The endosymbiotic theory proposes that eukaryotic cells arose from living communities formed by prokaryotic organisms.Evidence: Similarities between mitochondria, chloroplasts and bacteria. (DNA, ribosomes and binary fission)
12 17.3 Patterns of EvolutionMacroevolution: large-scale evolutionary patterns and processes that occur over long periods of time.Six Topics:Extinction: mass extinctions opened ecological opportunities for surviving organisms. (i.e. dinosaurs replaced by mammals and birds)Adaptive radiation: many species evolving from a single or small group of species (Fig )Convergent evolution: different species from similar climates resemble each other (Fig )
13 Six Topics: (Skipped topic 6) 17.3 Patterns of EvolutionMacroevolution: large-scale evolutionary patterns and processes that occur over long periods of time.Six Topics: (Skipped topic 6)Coevolution: organisms closely connected by ecological interactions evolve together (Fig )Punctuated equilibrium: stable periods and rapid periods of evolution (Fig )Changes in developmental genes: expression of hox genes greatly effects development. (17-26)