Fossils

Objective: TSW understand that populations of organisms change over time

Cornell Notes

• Dark Green – Left side of the line

• Brown – Right side of line

• Blue– Read Only -- Notes not required

• Red – Review questions -- Notes not required

Paleontology -Study of fossils, ancient life forms, and their evolution

Paleontologist

Fossil - Preserved remains or traces of an organism that lived in the past

• Fossils preserved in rock form from –

• bones, shells, and other physical remains (Usually not from soft tissue)

• black layer of carbon in the shape of an organism

• nests, tracks, trails, or other evidence left by an animal

• Amber – primarily

insects caught in tree sap

Fossils form –

• Impressions, molds, and casts

• Impression - left in mud or sediment (Broken down tiny bits of rocks, shells & other materials)

• Mold – empty space created by an impression or hardened part dissolves

• Casts – formed when a mold is filled in with sediment that hardens into stone

Preserved remains – 1. Fossils in Ice

Suppose a woolly mammoth is walking on top of a glacier and slips into a crack and gets trapped in the ice. The animal freezes and gets preserved in the ice  until the glacier thaws (melts) thousands of years later.

2. In tar pits (dark sticky form of oil)e.g. Rancho La Brea Tar Pits

When these photographs were taken around 1910, the location depicted was described as "the Salt Creek oilfields, 7 miles west of Los Angeles."

Wooly Mammoths Trapped in Oil

- 3. Sticky sap from evergreen trees(Amber)

Petrified fossils -

• 1. Remains buried in sediments change to rock

• 2. Minerals in water soak into remains,

• 3. Water evaporates, then the minerals change them into rock

Homologous Structure – • Body part that provides evidence that point to a common ancestral

evolution.• They are anatomical parts of a body that may have different functions

but have the same structure

GradualismGradualism

• Evolution of new species by gradual accumulation of small genetic changes over long periods of time

• Slow and steady change in an organism

• Over a short period of time it is hard to notice any change

Punctuated EquilibriumPunctuated Equilibrium• Stable periods of no change (genetic

equilibrium) interrupted by rapid changes resulting in rise of a new species

Determining a fossil’s age -

• A. Relative Dating -• Not accurate (Doesn’t tell the actual age)• Used to determine which of two fossils is

older• * Normally the higher up in the layers of

rock or sediment (sedimentary layers), the younger the fossil

• “Relatively speaking”, the murder occurred between sun down and sun up.

Determining a fossil’s age (continued)-

• B. Absolute Dating -

• Used to determine actual age of fossils

• Rocks near fossils contain radioactive elements (isotopes) used to calculate the age of the rock (and age of fossil)

Divisions of Geological Time Scale

• Eon – longest time unit

• Era – Next longest time unit

• Period – subdivision of an era

• Epoch – subdivision of a Period (shortest time unit)

Superposition – Layers of earth are arranged in a time sequence - Deeper layers are older than shallower layers

Following Slides #20-27

• Read over each slide before doing anything

• Red words are the instructions

• Yellow Captions on the bottom of each slide show:– Points for each slide and what’s required– i.e. Draw, label and color

• Notes are in Green and Brown

An organism dies in a location, such as a river bed, where sediments can rapidly cover its body.

Over time, pressure from additional sediment compresses the body, and minerals slowly replace all hard structures, such as bones

Erosion or Earthquakes may expose the fossils millions of years after formation.

Fossils in Rock • Draw and color each drawing (1/3 of page each)• Also write the caption next to each drawing

Draw the Triceratops skeleton here

Fossils in Rock Total – 15 pts: Drawn – 3 pts / Colored - 3 pts / Captions - 9 pts

Homologous Structure –

On Notebook paper - Sketch, labels and color similar bone structures (below), - Also label the Homologous Structure diagrams below (Human, Cat, Whale, and Bat)- You do not need to draw the diagram of the human and dog

Homologous Structures – 15 pts : Drawn – 10 pts / Colored - 4 pts / Caption -1 pts

Sedimentary Rock Formation   On the top half of a notebook page – Draw and color the picture below

Sedimentary Rock Formation – 10 pts Drawn – 5 pts / Colored - 5 pts

Sedimentary Rock -

• Little pieces of earth are eroded (wind, water, ice)

• Pieces (sediment) are washed downstream • Sediment settles to the bottom of the rivers,

lakes, and oceans.• Layer after layer of sediment are deposited on

top of each other (e.g. multi-layer cake)• Layers are pressed together• Until the bottom layers slowly turn into rock

(e.g. sandstone, limestone, shale)

• On the bottom half of the notebook page below your Sedimentary Rock Drawing

• Write the following 6 bullets

Sedimentary Rock Formation – 20 ptsDrawn – 5 pts Colored – 5ptsBullets – 10 pts (Deduct 2 pts per bullet -6 bullets)

Fossil Record -•Geological Time Scale = Relative Time Scale •Shows sequence of

events in order•Not very accurate

Geologic Time Scale Total 20 pts: Drawn – 6 pts Colored – 4 pts Labeled – 10 pts

• Draw and Label the Fossil Record• Start by listing each Period on lines of notebook paper• Then write in those years representing the periods, the ERAs, Phanerozoic Eon, and

Precambrian • Use a ruler to draw your column lines• Color by your Periods by ERA, Color the EON and Precambrian separately• Then write note below for the Fossil Record

Mold & Cast • On the top half a notebook page

– Draw two 3-toed dinosaur foot prints – Label #1 - “Mold” – empty space created by an

impression – Label #2 – “Cast”- Mold is filled in w/sediments,

then hardens to stone – Color them differently

Mold and Cast Total - 10 pts : Drawn – 4 pts / Colored - 4 pts / Labeled -2 pts

Relative Dating (Not accurate)

• On the bottom half of your notebook page below your Mold and Cast Drawings • Draw and color the diagram • Include two fossils buried at different sedimentary rock depths 

--Don’t include Numerical Dating

Relative Dating – 10 pts: Drawn – 5 pts Colored - 3 pts / Labeled - 2 pts

Preserved Remains

1 – In Ice – Draw any dinosaur trapped in ice

2 – In Tar Pits

- Draw the example using Slide 9

3 – In Amber – sticky sap from trees

- Draw some insects trapped in an amber egg

(Refer to Slide 10

• On notebook paper – • Draw and color each drawing (1/3 of page each)• Also write the caption next to each drawing

Preserved Remains - 10 pts : Drawn – 6 pts / Colored - 3 pts / Labeled - 3 pts