Geological Time Scale/Paleontology Lab



Paleontology Lab for Non-Majors in Introductory Level Geology Class

Range Through Chart and Diversity Curve Lab

Author: Dr. Kate Bulinski

Affiliation: Bellarmine University

Email: kbulinski@bellarmine.edu

Description of Assignment:

In advance of this assignment, students will hear a lecture discussing the major events throughout the history of life, including but not limited to: the Cambrian Explosion, the Ordovician Radiation, the "Big Five" mass extinctions and they will be shown the Sepkoski Curve. Additionally students will be introduced to major groups of organisms, mostly at the class and order level.

The assignment involves plotting the ranges where certain groups of organisms originated and went extinct on a range through chart. In this sample assignment, 20 taxonomic groups are provided with their origination and extinctions.

Studenst will then use this chart to generate a diversity curve based on the numbers of organisms that originate and persist through geological time periods. For example, if 11 taxa originate in the Cambrian, and 6 more in the Ordovician, and none go extinct, the value plotted for the Cambrian is 11 and 17 for the Ordovician.

Students will interpret the range through chart and the graph they generate in excel to answer several questions relating to the major mass extinctions and diversifications. Students will also draw from information presented in class.

This activity reinforces the major events in the history of life, increases familiarity with where certain groups of organisms are found sequentially in the fossil record and requires that students use excel to create a graph.

Potential Modifications:

-Organisms may be changed to those that the students have encountered in a previous labs

-This lab can be expanded to include more organisms

-This assignment may be paired with a systematic lab where students also must identify and describe fossils around the classroom that belong to these groups

-Organisms used could be of any taxonomic rank. I used Class, Subclass and Order since these encompassed many of the organisms the students learned about in lecture. You could use just bivalve genera for example and generate a diversity curve for just this group.

Range Through Chart and Diversity Curve Lab

Today you will be using the origination and extinction times of a range of fossil organisms to illustrate a major mass extinction event in the history of our planet while observing several different types of fossil organisms.

PART I: Each organism has a period of time where it originated and a period when it went extinct (if it in fact went extinct). Indicate this range on the range chart for each organism by first writing the taxon name in a column at the bottom and then shading in the range.

Fossil 1 Class Edrioasteroidea Range: Cambrian-Permian

Fossil 2 Class Articulata Range: Cambrian- Recent

Fossil 3 Subclass Ammonoidea Range: Silurian-Cretaceous

Fossil 4 Order Rugosa Range: Ordovician-Permian

Fossil 5 Order Tabulata Range: Ordovician-Permian

Fossil 6 Class Blastoidea Range: Ordovician-Permian

Fossil 7 Class Rostroconchia Range: Cambrian-Permian

Fossil 8 Class Gastropoda Range: Cambrian- Recent

Fossil 9 Class Stenolaemata Range: Ordovician-Recent

Fossil 10 Class Trilobita Range: Cambrian-Permian

Fossil 11 Order Scleractinia Range: Triassic- Recent

Fossil 12: Class Crinoidea Range: Ordovician- Recent

Fossil 13 Class Echinoidea ` Range: Ordovician-Recent

Fossil 14 Class Bivalvia Range: Cambrian-Recent

Fossil 15 Subclass Nautiloidea Range: Cambrian- Recent

Fossil 16 Class Stromatoporata Range: Ordovician-Cretaceous

Fossil 17 Class Eurypterida Range: Cambrian-Permian

Fossil 18 Class Graptolithina Range: Cambrian-Carboniferous

Fossil 19 Class Conodonta Range: Cambrian-Triassic

Fossil 20: Class Insecta Range: Silurian-Recent

Geological Time Scale

(modified from )

[pic]

Write Taxon Names Here(

Range Through Chart

| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |

Part II: Constructing a Diversity Curve

For each of the geological periods on the time scale, tally up the number of organisms that originated or exist during that time period. Plot these numbers on a line graph using Excel to generate a diversity curve of the number of taxonomic groups existing through time.

Label the X and Y axes, provide an appropriate title, and make sure you use the geological time periods as categories on the x-axis.

(See separate Excel file for example graph)

Part III Questions:

1) Based on the range chart you constructed, when does the largest extinction event occur and how many of the twenty organisms go extinct then?

The Permian, seven organisms.

2) What caused this extinction?

Students may provide varying answers based on what they are taught in class. Acceptable answers may include: widespread ocean anoxia, climate change (global warming), volcanism, stopping of ocean circulation, change of orientation of continents (Pangaea) among other things…

3) Which major extinction caused ammonoids to go extinct? What caused this extinction?

The Cretaceous (K-T) extinction, cause generally attributed to a large meteorite impact.

4) During what geological period do the most taxa originate and what is the name of this origination event?

Cambrian (11 taxa originate) , The Cambrian Explosion

5) During what geological period to the second largest number of taxa originate and what is the name of this event?

The Ordovician (6 taxa originate), The Ordovician Radiation

6) Notice when the three orders of coral originate and go extinct. Explain in a few sentences what the fossil record of corals looks like.

During the Paleozoic, Rugose and Tabulate corals exist and are found until the Permian Extinction. After the Permian, Scleractinian Corals are found and persist until today. This suggests that the Permian Extinction was unfavorable to Rugose and Tabulate orders, and a small number or coral organisms lived through the extinction event, and began to diversify from the Triassic until today. It would be logical to suggest that Scleractinian corals fill the niche left behind by the extinct coral orders.

7) How many of the 20 taxa are extant today?

Nine of the 20 taxa from this assignment are extant.

8) Provide three similarities and three differences between the diversity curve you generated and the Sepkoski Curve. Why are they different?

Similarities: The Cambrian Explosion

The Ordovician Radiation

The Permian Extinction

Differences: The Sepkoski Curve depicts family-level organisms; this curve is at the Order level and above.

The Sepkoski Curve increases towards the present day, this curve decreases.

The Sepkoski Curve depicts all five mass extinctions, ours truly only shows one.

They are different because of the resolution of taxonomy and the number of taxonomic groups considered (20 vs. hundreds).

9) If you constructed a range through chart of fossil genera, would you expect their ranges in the fossil record to be longer or shorter? Why?

Shorter. Higher taxonomic groups have long ranges because they have many organisms that have the chance to persist through geological time and extend the range of the order, or class. A genus has fewer representative lower taxonomic representatives (i.e., just species) and are more vulnerable to extinction as a result.

10) Why do you not find many fossils in the rock record before the Cambrian?

Multicellular organisms did exist before the Cambrian but generally did not produce shells. Changes in the atmosphere and oceans (e.g., the prevalence of oxygen and nutrients) provided favorable conditions to foster an “explosion” of diversification coupled with organisms that produced readily preservable hard parts.

-----------------------

Carboniferous

................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download