Untitled Flashcards Set

17.3: Evidence for Evolution

• Fossil record- represents the history of life on earth recorded in the remains for traces of organisms

  • to be a fossil it must be a least 10,000 years old

    • mammoths are found in ice in siberia

    • many organisms are encased in amber

• Petrification- the living material is replaced with minerals, happens to skeletal parts and wood

• The earth’s strata (layers) are used to piece together the story of life

• Before the use of fossils catastopshis c ould not explain the successive changes that link organisms in groups

  • a group of fossils (Archareopterx) are the intermediate between birds and reptiles

  • Eustrophteron- an amphibious fish

  • Seymouria- reptile like amphibian

• the fossils allow palentolgistss to find the order in which vertebrates (backboned animals) evolves from fish to amphibians, etc.

• George Gaylord Simpson estimated that 99.9% of all species will eventually become extinct

• Phyletc gradualism

  • evolutionary chang is slow

  • it is applicable to the evolutionaly r history of Equus

  • Gould, Niles Eldredge and Steven stanley proposed another model, the punuta ted equaliburim

    • uses organisms called “living fossils’ because of their resemblance to an fossil ancestor

    • cynobracteria has not changed for over 3 billion years

• biograpchicla evidence

  • Darwin saw that south america lacked rabbits although the environment was suited for them

  • he concluded that they must have evolved somewhere else and could not have made it to South America

  • Geographical isolation allowed speciation

• Anatomical evidence

  • vertabrate forlime used for flight

    • birds and bats

  • all vertebrates contain the same sets of bones organized in different grades

  • they were a common ancestor and are homooglus structures

  • the opposite analogous structures serve the same purpose but they are not constructed similarly; no common ancestor

  • vestigal structure are feacutes that are not needed anymore

  • Almost all living organism use the same basic molecules including dna

  • vertabreas and antrhopods have similar base sequences