Fossils -are the remains of life that are preserved within sediments and sedimentary rocks.
Paleontology -is the study of fossils linking concepts of geology and biology to understand prehistoric life over geologic time.
So to produce a fossil, two conditions must be observed:
The organism must possess hard parts (bones, teeth, etc.), and
Rapid burial of the remains increases the chance of preservation.
Permineralization- This occurs when pores and open spaces in tissue (such as bone and wood) are filled with minerals precipitated from mineral-rich solutions such as groundwater.
moldsandcast- When organisms buried in sediment dissolve or decay away
mold- leaves behind hollow space
cast- If minerals eventually fill in this hollow space
Amber- exceptionally preserved well, often still containing their soft parts.
Carbonization- This happens when these organisms are buried in sediment and eventually dissolve, leaving behind a thin layer of carbon outlining the organism’s shape.
Freezing -organisms can also be exceptionally preserved when they are encased in ice.
TraceFossils- can tell a lot about how an organism lived–how it moved, what it ate, and other types of behavior.
geologic time scale (older - younger)
hadean eon- formation of the earth
archean eon- blue-green algae start to produce
proterozoic eon- multicellular life emerges
phanerozioc- abundant of animal and plant life existed
phanerozoic era (older-younger)
paleozoic
mesozoic
cenozioc
4.6 BYA: Formation of the Earth
530 MYA: Cambrian explosion (sudden appearance of new animals in the fossil record)
11.8 KYA - Present: Holocene; current epoch
Absolute vs. Relative Dating
absolutedating-quantitative, gives numerical age [Example: Using radioactive decay (half-life) of a radioactive material to determine the age of a rock]
relativedating- qualitative, arranges object in time [Using a common fossil in two areas (index fossil) to compare what happened at a specific time period
geologic time scale (GTS) is a tool geologists use to classify and date rocks and fossils. Instead of numerical ages, time is divided into eons, eras, periods, epochs, and ages