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What do you notice?. What do you notice?. What do you noticed?. What do you notice?. ______________________of Evidence for the Theory of Evolution. 1.____________ Evidence of Evolution. Fossils Rock fossils are created when three events occur organism buried in sediment

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______________________of Evidence for the Theory of Evolution

1 evidence of evolution
1.____________ Evidence of Evolution

  • Fossils

  • Rock fossils are created when three events occur

    • organism buried in sediment

    • calcium in bone or other hard tissue mineralizes

    • surrounding sediment hardens to form rock

Fossil evidence of evolution
Fossil Evidence of Evolution

  • Absolute dating:

  • Relative dating:

  • Isotopes, like U238, transform at precisely known rates into nonradioactive forms.

  • The rate of decay is known as an isotope’s half-life

Fossil evidence of evolution1
Fossil Evidence of Evolution

Radioactive Decay

Fossil evidence of evolution2
Fossil Evidence of Evolution




the course

of life through


Fossil evidence of evolution3
Fossil Evidence of Evolution

  • Fossils

  • The oldest known bird fossil is the

  • It is intermediate between bird and dinosaur

  • Possesses some ancestral traits and some traits of present day birds

  • Archaeopteryx was first found in 1859

Fossil evidence of evolution4
Fossil Evidence of Evolution

Fossil of Archaeopteryx

Fossil evidence of evolution5
Fossil Evidence of Evolution

Recent discoveries

  • Four-legged aquatic mammal

    • Important link in the evolution of whales and dolphins from land-dwelling, hoofed ancestors

  • Fossil snake with legs

  • Tiktaalik: a species that bridged the gap between fish and the first amphibian

  • Oysters: small curved shells to large flat shells

Fossil evidence of evolution6
Fossil Evidence of Evolution

Whale “missing links”

Fossil evidence of evolution7
Fossil Evidence of Evolution

Evolutionary change in body size and toe reduction of horses

Homologous structure

  • Similar features that originate in a shared ancestor (derive from same embryonic structure)

  • Can result from modifications that change an original feature to 2 extremely different types (wing and arm)

Homologous structures

Anatomical evidence for evolution
Anatomical Evidence for Evolution

  • 2. Homologous structures:

  • structures with common evolutionary origins (can be similar in structure, function, or both)

  • The bones in the forelimb of mammals are homologous structures

  • Different functions, same ancestor structure

Anatomical evidence for evolution1
Anatomical Evidence for Evolution

Homology of the bones of the forelimb of mammals

Analagous feature

Serve identical functions and look similar

No anatomical/embryological similarity

Wing developed independently and differently in more-recent ancestors of each animal

3. Analogous structures:

Anatomical evidence for evolution2

Vestigial structures of a whale: hind leg bones!?

Anatomical Evidence for Evolution

  • Vestigial structures:

4 vestigial structures
4. Vestigial Structures


  • Muscles for wiggling ears (similar muscles that animals use to move ears to hear predators or prey)

  • Tail bones present in human and all vertebrate embryos. In humans, the tail is reduced; most adults only have three to five tiny tail bones and, occasionally, a trace of a tail-extending muscle.

  • Appendix Structure which presumably had a digestive function in some of our ancestors, like the cecum of some herbivores. In humans, it varies in length from 5–15 cm, and some people are born without one.

Vestigial structures cont
Vestigial Structures cont.

  • Wisdom teeth There are two possible reasons why the wisdom teeth have become vestigial. The first is that the human jaw has become smaller than its ancestors -and the wisdom teeth are trying to grow into a jaw that is much too small. The second reason may have to do with dental hygiene. A few thousand years ago, it might be common for an 18 year old man to have lost several, probably most, of his teeth, and the incoming wisdom teeth would prove useful. Now that humans brush their teeth twice a day, it's possible to keep one's teeth for a lifetime. The drawback is that the wisdom teeth still want to come in, and when they do, they usually need to be extracted to prevent any serious pain.

Vestigial structures cont1
Vestigial Structures cont.


  • have tiny femurs (leg bone)


  • Fingernails on their fins

    Blind cave fish

  • Nonfunctional eyes

Anatomical evidence for evolution3
Anatomical Evidence for Evolution

  • Strongest anatomical evidence supporting evolution comes from comparisons of how organisms develop.

  • Early vertebrate embryos possess pharyngeal pouches (gill slits) that develop into:

    • In humans: glands and ducts

    • In fish: gills

5. ________________ Evidence for Evolution

Developmental similarities reflect descent from a common ancestor


  • All

  • Two closely-related organisms will have similar DNA, RNA, and protein (amino acid) sequences.

  • This also gives evidence of a common ancestor.

Convergent evolution
Convergent Evolution

  • Biogeography: the study of the geographic distribution of species

    • Some plants and animals have similar appearance but are only distantly related

  • Convergent evolution: the independent development of similar structures in organisms that are not directly related

  • Convergent evolution is usually seen in animals and plants that live in similar environments

Convergent evolution1
Convergent Evolution

  • Marsupials and placentals

    • Marsupials: young are born in an immature condition and held in a pouch until they develop

    • Placentals: young are not born until they can safely survive in the external environment

Convergent evolution3
Convergent Evolution

Convergence among fast-swimming predators