Fossils: Their Place in Time and Nature

The Past: Evidence for the present

Questions addressed:

• what are fossils?

  • can pretty much be anything (not just dinos)

• what do fossils tell us about the past?

  • construct past environments, evolutions

• what methods do anthropologists and other scientists use to study fossils?

  • excavation, very risky

Fossils and the Principles of Faunal Succession

• william smith (1769-1839)

• principle of faunal succession

  • strata

• fossils found in one layer were older or younger than the fossils below or above it.

  • not always the case but it very rare

Fossils: A Variety of Forms

• not just dinos

Fossils: Memories of the Biological Past

• taphonomy

• the study of how organisms decay and become fossils

• introduced to paleontology in 1949 by Ivan Efremov

• Basically, the study of everything that happens to an organism after it dies until it is recovered by an archaeologist, paleontologist, forensic anthropologist, etc.

  • includes things that happen in the lab too

    • what qualifies as absoultue dating

    • would hoinins splti again? has their been a recored spilt in human lifetime?

types of fossils and the limitations of the fossil record

• bones in hole

• footprints

  • paleontologists have searched for fossils only in some places, so have not discovered all fossil areas.

    • safety reasons, cant exavate in war zone

  • fossils are well preserved in some places and not in others

  • rock sequences are not always complete when they are discovered

    • because of erosion

Time in perspective

• anthropocene

  • proposed new geological epoch

  • time period that we are currently in

  • commenced from the start of significant human impact on Earth’s geology and ecosystems, including, but not limited to, anthropogenic climate change

    • once we started planting crops it fuhed up

Geological time: earth history

• Steno’s Law of Superposition

  • nicolaus steno (1638-1686)

  • law of superposition

  • relative dating

  • stratigraphic correlation

    

stratigraphic correlation

• Krakatoa, indonesia

• 1883

  • anything under the Krakatoa ash layer, it came before

  • anything above the Krakatoa ash layer, it can after

    • can tell the difference with the chemical signature

Chemical dating

• fluorine dating

  • bones buried deeper would have more fluorine than others

• krapina neanderthal fossils

• dragution gorjanović-kramberger

biostratigraphic (faunal) dating

• index fossils

  • fossil pig molars

  • pigs in the current days thicker emanal than its predecessors, so if you find a pig with a thinner emanal, then it must be ancestor of our current pigs

    • thicker emanal = younger

    • thinner = older

  • irish elk

    • went extinct in 600 mya, anything in that layer is 600 ya, anything above it is younger

Cultural dating

• starts off from big rocks to shaper knifes

• with more knowlegde, we evole

  • big rocks —> circle rocks = wheel = wagon = car = super car

relative and absolute dating (EXAM)

Absoute methods

• tree ring dating

  • wider white section is not growth maybe drought

  • closer together = wet year

Radiocarbon dating and half lives (explain again)

• carbon decays into nitrogen

• only radioactive decays

• all living things absorb carbon

Radiometric dating

• clock in a rock

• fission track dating ankylosaurus

  • date the rock

    • found by volcanos

paleomagnetic

Nonradiometric dating methods

• amino acid dating

  • racemization

• electron spin resonance dating

• thermoluminescence dating

Different dating techniques

Genetic dating

Reconstruction of ancient environments and landscapes

• foraminifera

  • high oxygen-18 = low temps

  • low oxygen-18 = high temperature

Chemistry of Acient Remains and Ancient Soils

• C3 plant photosynthesis

  • wet-wooded plants

  • avoid carbon-13

• C4 photosynthesis

  • grassland plants

  • high in carbon-13