Index Fossils + Types of Fossils

Index Fossils + Types of Fossils

Bell Ringer

• Environmental factors = anything that is not determined by an organism's genes.

• If ten plants have the same genes, only the only thing that will cause them to grow to different heights are the different amounts of water and light.

Bell Ringer

• Genes code for specific traits

• Genes are made out of DNA

Announcements

• Homework due Thursday

• Sign up for Calendly conference if you haven't yet

• Quiz tomorrow

Agenda

• Bell Ringer/Announcements

• Review Index Fossils

• Introduction to the Types of Fossils

• Quizizz Game

• Exit Ticket

Multiple Choice

Which two characteristics must an organism have to be used as an index fossil?

• geographically limited and existed for a geologically long period of time

• geographically limited and existed for geologically short period of time

• geographically widespread and existed for a geologically short period of time

• The species must look similar to several other species.

Index Fossils

• Two traits:

• 1. Geographically Widespread

• 2. Organism only existed for a short period of time

Multiple Choice

The diagram shows the fossils of organisms (A, B, C, and D) deposited in rock layers in four different areas of a region.

Which organism is an index fossil, and why?

• Organism A. It is found in all four rock layers of Area 2.

• Organism B. It is found in different rock layers across the four areas.

• Organism C. It is found only in one rock layer across all the four areas.

• Organism D. It is found only in one rock layer of Area 4.

Multiple Choice

Upon examining the fossil layers collected from outcrops of three different regions, a researcher concluded that some of the layers contained index fossils. The images show the index fossil key and the fossil layers from the three outcrops.

Which rock layers are likely the same age?

• rock layer A and rock layer Z

• rock layer A and rock layer P

• rock layer C, rock layer R, and rock layer Y

• rock layer B, rock layer Q, and rock layer X

Multiple Choice

The geologic cross section diagram shows undisturbed rock layers with index fossils from two regions (A and B). The two index species are identified in the index fossil key.

Which answer option correctly describes the relative ages of the rock layers in the diagram?

Multiple Choice

The diagram shows outcrops (A, B, and C) excavated from three different regions. The rock layers and the index fossils in each outcrop are labeled in the image.

Assuming the rock layers in the outcrops were not overturned, which layers in the outcrops are the same ages?

• Layers 1, 6, and 11

• Layers 1, 10, and 16

• Layers 2, 7, and 12

• Layers 5, 10, and 16

Moving on... Types of Fossils!

Types of Fossils

• 1. Preserved Fossils

• 2. Petrified Fossils

• 3. Mold Fossils

• 4. Cast Fossils

• 5. Trace Fossils

1. Preserved/True Form Fossils

• A preserved fossil, also known as a "true form fossil," is one that remains intact including soft tissue and muscle. Preserved fossils are very rare.

• Typically involves the organism becoming entrapped and preserved. Most commonly, these form when an organism is frozen.

• Two examples: insects being trapped in tree resin; wooly mammoths becoming frozen during the ice age

2. Petrified Fossils

• Form when minerals replace the structure of an organism.

• This process, called permineralization, occurs when groundwater saturates the remains of the buried organism.

• As the water evaporates the minerals remain, eventually filling in the spaces left as the organism slowly decays

3. Mold Fossils

• The impression of the organism left in sediment is called a mold fossil.

4. Cast Fossils

• The mineralized sediment that fills the mold recreates the shape of an organism's remains. This is called a cast fossil.

5. Trace Fossils

• Geological records of the activities and behaviors of past life. Some examples include rock evidence of nests, burrows, and footprints.

• Formed when an organism makes a mark in mud or sand. The sediment dries and hardens.  It is covered by a new layer of sediment. As the sediment turns to rock, the mark becomes fossilized.

Multiple Choice

What type of Fossil do you think is more common: petrified fossils or trace fossils?

(Reminder: body fossils are part of an actual animal or plant, and trace fossils are fossilized footprints/nests/burrows/trails of an organism)

• Petrified fossils

• Trace fossils

Multiple Choice

Identify the Type of Fossil (hint: the organism's whole body is preserved)

• Petrified

• Trace

• Mold

• Cast

• Preserved

Multiple Choice

Identify the Type of Fossil (hint: this is a nest)

• Petrified

• Trace

• Mold

• Cast

• Preserved

Multiple Choice

Identify the Type of Fossil (hint: this is an impression of an organism)

• Petrified

• Trace

• Mold

• Cast

• Preserved

Quizizz

• Let's put your knowledge to the test!

• Open up a new tab and go to joinmyquiz.com

• Enter the code in the chat box.

Exit Ticket

• Complete the Exit Ticket in Canvas

• When you're finished, you're good to go.

• Have a great rest of your day!