Email Print Share

Return Home

Extinct group of solitary horn corals Download this image.
July 28, 2011

Prehistoric Coral (Image 1)

A group of solitary horn corals, an extinct group of corals that belong to the Paleozoic evolutionary fauna. They are preserved in carbonate and are Ordovician in age (~450 million years old). They were found in southwestern Wisconsin. [See related image Here.]

More about this Image
Recent research suggests that it is the ocean, and in particular the epic ebbs and flows of sea level and sediment over the course of geologic time, that is the primary cause of the world's periodic mass extinctions during the past 500 million years.

A National Science Foundation supported-study by Shanan Peters, a University of Wisconsin-Madison assistant professor of geology and geophysics, found that changes in ocean environments related to sea level exert a driving influence on rates of extinction, which animals and plants survive or vanish, and generally determine the composition of life in the oceans. Since life began on Earth 3.5 billion years ago, scientists believe there may have been as many as 23 mass extinction events, and, during the past 540 million years, there have been five, well-documented mass extinctions, primarily of marine plants and animals, with as many as 75-95 percent of species lost.

For the most part, scientists have been unable to pin down the causes of such dramatic events. In the case of the demise of the dinosaurs, scientists have a smoking gun, an impact crater that suggests dinosaurs were wiped out as the result of a large asteroid crashing into the planet. But the causes of other mass extinction events have been murky, at best. To learn more, see the UW-Madison news release, "Ebb and flow of the sea drives world's big extinction events." (Date of Image: 2008)

Credit: Shanan Peters, University of Wisconsin-Madison

See other images like this on your iPhone or iPad download NSF Science Zone on the Apple App Store.


Images and other media in the National Science Foundation Multimedia Gallery are available for use in print and electronic material by NSF employees, members of the media, university staff, teachers and the general public. All media in the gallery are intended for personal, educational and nonprofit/non-commercial use only.

Images credited to the National Science Foundation, a federal agency, are in the public domain. The images were created by employees of the United States Government as part of their official duties or prepared by contractors as "works for hire" for NSF. You may freely use NSF-credited images and, at your discretion, credit NSF with a "Courtesy: National Science Foundation" notation.

Additional information about general usage can be found in Conditions.

Also Available:
Download the high-resolution JPG version of the image. (1 MB)

Use your mouse to right-click (Mac users may need to Ctrl-click) the link above and choose the option that will save the file or target to your computer.