Paleocene Turtles and Crocodilians Directly above the Cretaceous/Tertiary (K/T) Boundary in Pulaski County, Illinois

By Holman, J. Alan | Michigan Academician, Summer 2002 | Go to article overview

Paleocene Turtles and Crocodilians Directly above the Cretaceous/Tertiary (K/T) Boundary in Pulaski County, Illinois


Holman, J. Alan, Michigan Academician


ABSTRACT

During the earliest part of the Paleocene (Danian Age), the Mississippi Embayment extended into southern Illinois. Recently, fossils from this interval were found immediately above the K/T(Cretaceous/Tertiary) boundary in the Clayton Formation near Olmsted, Pulaski County, Illinois. Bryozoans, gastropods, and pelecypods dominate the fauna, and sharks are common. Rare fossils include annelid worms, crabs, a spiny lobster, a ratfish, a ray, a few bony fishes, and the reptiles reported here Reptiles have not been previously reported from the Paleocene or Eocene of any state or province bordering the Great Lakes. Moreover, all reptiles reported here represent survivors of the massive extinction of the dinosaurs and great sea reptiles at the end of the Cretaceous. Turtles are represented by remains of a large sea turtle of the modem genus Chelonia and a softshell turtle assigned to cf. Trionyx, a modern genus of the family Trionychidae; a small crocodilian is also represented. Previously, the Clayton fauna was sai d to represent a near shore brackish to nearly marine environment. Based on the Clayton reptiles, one can further refine this interpretation by suggesting a riverine, coastal environment in a semitropical or tropical climate.

INTRODUCTION

Reptilian fossils directly above the boundary between the Cretaceous and Tertiary Periods (K/T boundary) are important because they represent survivors of the massive reptilian extinction episode at the end of the Cretaceous, which not only resulted in the complete extermination of the dinosaurs, but also the demise of the last of the great sea reptiles. Therefore, the discovery of three fossil reptiles in the Clayton Formation of Pulaski County, in extreme southern Illinois (Figure 1) directly above the Cretaceous/Tertiary (KIT) boundary is of more than local importance, as Paleocene reptiles have not previously been reported from any state or province bordering the Great Lakes. These fossils were found in the near shore marine sediments of the Mississippi Embayment (Figure 2), an inland sea that penetrated northward to extreme southern Missouri and Illinois in the Early Paleocene. The fossils were collected from spoils of the Golden Cat Company Clay Pit.

The Clayton Formation (Earliest Paleocene, Danian Age) is immediately above the K/T boundary. The sedimentary material that underlies the Clayton Formation sediments forms the Owl Creek Formation which represents the Maastrichtian Age of the Late Creraceous (Figure 3).

The Clayton Formation, itself, is overlain by the later Paleocene Porters Creek Formation (not figured), which contains the material that is mined to manufacture the product "Kitty Litter."

The lithology of the Clayton Formation is quite distinct from that of either the overlying Porters Creek or underlying Owl Creek Formations, and contains a clay pit (Golden Cat Company Clay Pit) which consists of 5 to 6 meters of bioturbated, dark green, glauconitic, micaceous, fine to medium sands alternating with layers of dark gray clay. Fossils were collected and processed from spoil piles from the clay pit under the direction of Dr. John E. Utgaard of the Department of Geology of Southern Illinois University, Carbondale Illinois. The collectors retrieved 8750 fossil specimens that are thought to represent a fair representation of the fossil assemblage.

THE NON-REPTILIAN FAUNA

The Invertebrate Fossils

The preponderance of the fossils collected (91%) represented eight species of invertebrates. These included the gastropod Turritella alabamiensis (39% of the 8750 fossils), which was mainly represented by phosphatic internal molds. The nodular bryozoan Conopeum damicornis (30% of the total fossils) encrusted most of the mollusks at the site and even the base of some shark's teeth. Pitar? ripleyanus (8% of the total), apelecypod, was a shallower burrower. A pelecypod of the oyster genus Ostrea, O.

The rest of this article is only available to active members of Questia

Sign up now for a free, 1-day trial and receive full access to:

  • Questia's entire collection
  • Automatic bibliography creation
  • More helpful research tools like notes, citations, and highlights
  • Ad-free environment

Already a member? Log in now.

Notes for this article

Add a new note
If you are trying to select text to create highlights or citations, remember that you must now click or tap on the first word, and then click or tap on the last word.
One moment ...
Project items

Items saved from this article

This article has been saved
Highlights (0)
Some of your highlights are legacy items.

Highlights saved before July 30, 2012 will not be displayed on their respective source pages.

You can easily re-create the highlights by opening the book page or article, selecting the text, and clicking “Highlight.”

Citations (0)
Some of your citations are legacy items.

Any citation created before July 30, 2012 will labeled as a “Cited page.” New citations will be saved as cited passages, pages or articles.

We also added the ability to view new citations from your projects or the book or article where you created them.

Notes (0)
Bookmarks (0)

You have no saved items from this article

Project items include:
  • Saved book/article
  • Highlights
  • Quotes/citations
  • Notes
  • Bookmarks
Notes
Cite this article

Cited article

Style
Citations are available only to our active members.
Sign up now to cite pages or passages in MLA, APA and Chicago citation styles.

(Einhorn, 1992, p. 25)

(Einhorn 25)

1

1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

Cited article

Paleocene Turtles and Crocodilians Directly above the Cretaceous/Tertiary (K/T) Boundary in Pulaski County, Illinois
Settings

Settings

Typeface
Text size Smaller Larger
Search within

Search within this article

Look up

Look up a word

  • Dictionary
  • Thesaurus
Please submit a word or phrase above.
Print this page

Print this page

Why can't I print more than one page at a time?

Full screen

matching results for page

Cited passage

Style
Citations are available only to our active members.
Sign up now to cite pages or passages in MLA, APA and Chicago citation styles.

"Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn, 1992, p. 25).

"Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn 25)

"Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences."1

1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

Cited passage

Welcome to the new Questia Reader

The Questia Reader has been updated to provide you with an even better online reading experience.  It is now 100% Responsive, which means you can read our books and articles on any sized device you wish.  All of your favorite tools like notes, highlights, and citations are still here, but the way you select text has been updated to be easier to use, especially on touchscreen devices.  Here's how:

1. Click or tap the first word you want to select.
2. Click or tap the last word you want to select.

OK, got it!

Thanks for trying Questia!

Please continue trying out our research tools, but please note, full functionality is available only to our active members.

Your work will be lost once you leave this Web page.

For full access in an ad-free environment, sign up now for a FREE, 1-day trial.

Already a member? Log in now.