Featured Research

from universities, journals, and other organizations

Mass Extinction 250 Million Years Ago Sparked Dramatic Shift To Complex Marine Ecosystems

Date:
November 28, 2006
Source:
Field Museum
Summary:
The biggest mass extinction did more than eliminate species: It fundamentally changed the basic ecology of the oceans. Ecologically complex marine communities displaced simple communities, setting a pattern that has continued ever since. This striking change has escaped detection because previous research relied on single numbers -- such as the number of species alive at one time -- to track diversity. New research examines the relative abundance of marine life forms in communities over 540 million years.

In the Cretaceous about 80 million years ago -- well after the end-Permian mass extinction -- the ocean floor was dominated by complex ecosystems that had largely displaced the simple ecosystems. This photograph of a Field Museum diorama of the ocean floor during the Cretaceous shows many free-swimming, complex organisms, including the large ammonoid (in the center of the image) and the long nautiloids (with handlike ends). In addition, the ocean floor is littered with mobile clams and snails.
Credit: Photo graph of Field Museum diorama by Ron Testa, courtesy of The Field Museum

The earth experienced its biggest mass extinction about 250 million years ago, an event that wiped out an estimated 95% of marine species and 70% of land species. New research shows that this mass extinction did more than eliminate species: it fundamentally changed the basic ecology of the world's oceans.

Related Articles


Ecologically simple marine communities were largely displaced by complex communities. Furthermore, this apparently abrupt shift set a new pattern that has continued ever since. It reflects the current dominance of higher-metabolism, mobile organisms (such as snails, clams and crabs) that actually go out and find their own food and the decreased diversity of older groups of low-metabolism, stationary organisms (such as lamp shells and sea lilies) that filter nutrients from the water.

So says research published in Science on November 24, 2006. An accompanying article suggests that this striking change escaped detection until now because previous research relied on single numbers--such as the number of species alive at one particular time or the distribution of species in a local community--to track the diversity of marine life. In the new research, however, scientists examined the relative abundance of marine life forms in communities over the past 540 million years.

One reason they were able to do this is because they tapped the new Paleobiology Database (http://www.pbdb.org), a huge repository of fossil occurrence data. The result is the first broad objective measurement of changes in the complexity of marine ecology over the Phanerozoic.

"We were able to combine a huge data set with new quantitative analyses," says Peter J. Wagner, Associate Curator of Fossil Invertebrates at The Field Museum and lead author of the study. "We think these are the first analyses of this type at this large scale. They show that the end-Permian mass extinction permanently altered not just taxonomic diversity but also the prevailing marine ecosystem structure."

Specifically, the data and analyses concern models of relative abundance found in fossil communities throughout the Phanerozoic. The ecological implications are striking. Simple marine ecosystems suggest that bottom-dwelling organisms partitioned their resources similarly. Complex marine ecosystems suggest that interactions among different species, as well as a greater variety of ways of life, affected abundance distributions. Prior to the end-Permian mass extinction, both types of marine ecosystems (complex and simple) were equally common. After the mass extinction, however, the complex communities outnumbered the simple communities nearly 3:1.

The other authors are Scott Lidgard, Associate Curator of Fossil Invertebrates at The Field Museum, and Matthew A. Kosnik, from the School of Marine and Tropical Biology at the James Cook University in Townsville, Queensland, Australia.

"Tracing how marine communities became more complex over hundreds of millions of years is important because it shows us that there was not an inexorable trend towards modern ecosystems," Wagner said. "If not for this one enormous extinction event at the end of the Permian, then marine ecosystems today might still be like they were 250 million years ago."

These results also might provide a wake-up call, Wagner added: "Studies by modern marine ecologists suggest that humans are reducing certain marine ecosystems to something reminiscent of 550 million years ago, prior to the explosion of animal diversity. The asteroid that wiped out the dinosaurs couldn't manage that."

Lidgard added, "When Pete walked into my office with his preliminary results, I simply couldn't believe them. Paleontologists had long recognized that ecosystems had become more complex, from the origin of single-celled bacteria to the present day. But we had little idea of just how profoundly this one mass extinction--but not the others like it--changed the marine world."


Story Source:

The above story is based on materials provided by Field Museum. Note: Materials may be edited for content and length.


Cite This Page:

Field Museum. "Mass Extinction 250 Million Years Ago Sparked Dramatic Shift To Complex Marine Ecosystems." ScienceDaily. ScienceDaily, 28 November 2006. <www.sciencedaily.com/releases/2006/11/061126121112.htm>.
Field Museum. (2006, November 28). Mass Extinction 250 Million Years Ago Sparked Dramatic Shift To Complex Marine Ecosystems. ScienceDaily. Retrieved March 6, 2015 from www.sciencedaily.com/releases/2006/11/061126121112.htm
Field Museum. "Mass Extinction 250 Million Years Ago Sparked Dramatic Shift To Complex Marine Ecosystems." ScienceDaily. www.sciencedaily.com/releases/2006/11/061126121112.htm (accessed March 6, 2015).

Share This


More From ScienceDaily



More Plants & Animals News

Friday, March 6, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Giant Panda Goes Walkabout in Southwest China

Giant Panda Goes Walkabout in Southwest China

AFP (Mar. 6, 2015) — A giant panda goes walkabout alone at night in southwest China. Duration: 00:37 Video provided by AFP
Powered by NewsLook.com
Nesting Bald Eagle Covered in Snow Up to Its Neck

Nesting Bald Eagle Covered in Snow Up to Its Neck

Buzz60 (Mar. 6, 2015) — The Pennsylvania State Game Commission captured amazing shots of a nesting bald eagle who stayed on its nest during a snowstorm, even when the snow piled all the way up to its neck. Jen Markham (@jenmarkham) has the story. Video provided by Buzz60
Powered by NewsLook.com
Lack of Snow Pushes Alaska Sled Dog Race North

Lack of Snow Pushes Alaska Sled Dog Race North

AP (Mar. 6, 2015) — A shortage of snow has forced Alaska&apos;s Iditarod Trail Sled Dog Race to move 300 miles north to Fairbanks. The ceremonial start through downtown Anchorage will take place this weekend, using snow stockpiled earlier this winter. (March 6) Video provided by AP
Powered by NewsLook.com
Praying Mantis Looks Long Before It Leaps

Praying Mantis Looks Long Before It Leaps

Reuters - Innovations Video Online (Mar. 5, 2015) — Slowed-down footage of the leaps of praying mantises show the insect&apos;s extraordinary precision, say researchers. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins