Tracing Evolutionary

HistoryCHAPTER 15

15.1O Fossils chronicle the evolutionary

timelineO Eras in geologic timeO PrecambrianO PaleozoicO MesozoicO Cenozoic

Precambrian EraO 4.6 billion ya- 542 mya

O First fossils- prokaryotic cells (3.5 billion ya)

O Diverse invertebrates (600 mya) and algae

O Oxygen builds up in our atmosphere as the result of photosynthetic bacteria

Paleozoic eraO 542 mya-251myaO Cambrian explosion – many new

animalsO Colonization of land by arthropods

and land plants O FishO Tetrapods (amphibians)O Seed plants, Reptilian adaptive

radiationO Major extinction of many organisms

Mesozoic EraO 251 mya-65myaO Cone bearing plantsO Radiation of dinosaurs O Origin of mammals O Flowering plants O Major dinosaur extinction at end of

era

Cenozoic EraO 65 mya-present O Radiation of birds and mammalsO Origin of primates O Origin of hominids O Ice Ages

15.3 Continental driftO 1912- Alfred Wegener suggested that

all the land masses were once a single mass called Pangea

O Pangea broke apart and the continents drifted to there current locations creating geographic isolation

15.5 Mass Extinctions O Permian mass extnction (boundary

between Paleozoic and Mesozoic) 96% of all marine life O Volcanic eruption in Siberia ?

O Creataceous mass exntinction – dinosaur extinction O Asteroid collision? Climate change ?

Convergent EvolutionO Likeness suggests

relationships . . .however some likeness is the result of living in a similar environement NOT common ancestry

O Streamlined appearance of both whales (mammals) and sharks (cartilage fish)

Scientific naming O Linneaus – 18th century – Latin naming

system O DomainO KingdomO PhylumO ClassO OrderO FamilyO Genus + species = organism’s scientific

name

15.8 Cladistics O Forming family trees based on

shared traits O New branches have derived traits O “family trees” – cladograms