2009 Salina Intermediate Teacher Techology Training Camp - Assignment 2: Extinction Events Case Study

Case Study: Extinction Events

Imagine that you are a geologist working for the University of Michigan – Dearborn. On a recent fossil dig, you uncovered a new species, which looks similar to a trilobite. Using absolute dating, you discovered that the species was from the Cambrian period.

The new species has several distinct body parts. It has eyes, which are used to see underwater. Also, the new species has antennae, which it probably used to sense motion and heat. The new species also had soft tissue around its body, which made it vulnerable to larger predators. It used gills for breathing underwater and had 12 legs for walking. This new species lived underwater and was uncovered as a cast fossil in a layer of sedimentary rock. The population of this species was found near an area which was known to have high levels of plankton during the Cambrian period. Many of the fossils found are incomplete, with significant body parts missing.

It is uncertain what caused this new species to go extinct; however several theories have already been suggested. A possible first theory suggests that a change in the lake temperature caused the new species to become extinct. Evidence suggests that the temperature of the water increased by approximately 3 degrees Fahrenheit during the end of the Cambrian Period.

Another possible theory is that a meteorite strike caused the extinction of the new species. A 3 inch meteorite was recently uncovered on land near a small crater approximately 5 miles away from where the new species was found.

It is also possible that overhunting by predators may have caused the extinction of the new species. Since several incomplete fossils have been found, it is possible that other trilobites that lived in the lake or a new species overhunted this species. The predator trilobites were found as fossils in sedimentary rock that dated back to 300 years after the last of the new species fossils were found. Also, newer fish species were found in the lake during this time period.

A final possible cause for extinction is that increased competition over food may have caused the extinction of the new species. Many different types of trilobites ate plankton, which was very easy to find in the lake at the time. It is possible that the plankton may have become scarce for a brief time leading to increased competition. The other trilobites that ate the plankton were found as fossils in sedimentary rock that dated back to 300 years after the last of the new species fossils were found.

Your Task:

Comment on the following in a report to your department chair, Mr.Attee:

1. Species description: Briefly describe some of the important features of the new species and how it got its energy (or food).

2. Extinction Theory: Briefly describe how you think the new species became extinct and what evidence you have that supports your position.