Background Knowledge:
Background Knowledge:
Embedded Files
Trace fossils are clues that organisms left while still alive (eg. poop, footprints, eggs, nests). They tell a story about the animal's behavior and can be used to understand what the environment around them was like. Worm burrows in rocks are a type of trace fossil. They indicate that animals like worms were active and doing well during the time the rocks formed.
As they went up and down the sediment, burrowing organisms left trails and mixed the sediment around (see examples below). This is called bioturbation.
In this project, Dr. Diana Boyer uses size and abundance of worm burrows to interpret whether ocean environments during the Devonian Period had low oxygen (or "oxygen stress").
Ichnofabric indexing is the method used to measure the intensity of burrowing organisms preserved in ancient sediments. The data is used to determine what the oxygen levels were like in the ocean. Less burrowing organisms and intact layers of sediment mean that it is more likely the bottom waters of the ocean had low oxygen.
This is significant to uncovering the Devonian Extinction mystery because lack of oxygen (anoxia) in the oceans is know to be a cause of mass extinction events.
Work the Case:
Work the Case:
Below are five samples that were analyzed for bioturbation evidence. Unfortunately, the cards with Dr. Diana Lynne Boyer's notes were accidentally mixed up. Figure out which notes go with which rock sample by matching the letters in the bottom of the card with the number of the sample (found under each photograph).
Ichnofabric specimen (i)
Ichnofabric specimen (ii)
Ichnofabric specimen (iii)
Ichnofabric specimen (iv)
Ichnofabric specimen (v)
Samples are compared to an ichnofabric index according to fossil evidence of life, (from no life to abundant life) and given a number 1 to 5. Think about the two questions that follow, then check your answers below.
Question 1:
The samples above have been given numbers according to the index. By looking at the numbers of the ichnofabric specimens above and their matching cards, would you say the ichnofabric index is organized according to:
increasing bioturbation and oxygen (ie. specimen i with the lowest bioturbation and specimen v with the highest)?
or
decreasing bioturbation and oxygen (ie. specimen i would have the highest bioturbation and specimen v lowest)?
Question 2:
Some of the rocks that the researchers have found in Devonian extinction sites like New York are black shales that show possible anoxia (remember this means, the rocks formed in an environment with little oxygen).
Which of the specimens above is most likely to show anoxia/ low oxygen?
You should have picked up TWO more passkeys in this section, and you're almost at the end! You have one last challenge to solve, click on the arrow...
Page updated
Report abuse