Featured Research

from universities, journals, and other organizations

Prehistoric Mystery Organism Verified As Giant Fungus

Date:
April 24, 2007
Source:
University of Chicago
Summary:
Scientists have produced new evidence to finally resolve the mysterious identity of what they regard as one of the weirdest organisms that ever lived.

C. Kevin Boyce, Assistant Professor in Geophysical Sciences at the University of Chicago, with a slice of Prototaxites, a giant prehistoric fungus. The computer screen shows a chemical map of a magnified portion of the organism's cell walls.
Credit: Lloyd DeGrane photo

Scientists at the University of Chicago and the National Museum of Natural History in Washington, D.C., have produced new evidence to finally resolve the mysterious identity of what they regard as one of the weirdest organisms that ever lived.

Their chemical analysis indicates that the organism was a fungus, the scientists report in the May issue of the journal of Geology, published by the Geological Society of America. Called Prototaxites (pronounced pro-toe-tax-eye-tees), the organism went extinct approximately 350 million years ago.

Prototaxites has generated controversy for more than a century. Originally classified as a conifer, scientists later argued that it was instead a lichen, various types of algae or a fungus. Whatever it was, it stood in tree-like trunks more than 20 feet tall, making it the largest-known organism on land in its day.

"No matter what argument you put forth, people say, well, that's crazy. That doesn't make any sense," said C. Kevin Boyce, an Assistant Professor in Geophysical Sciences at Chicago. "A 20-foot-tall fungus doesn't make any sense. Neither does a 20-foot-tall algae make any sense, but here's the fossil."

The Geology paper adds a new line of evidence indicating that the organism is a fungus. The fungus classification first emerged in 1919, with Francis Hueber of the National Museum of Natural History in Washington, D.C., reviving the idea in 2001. His detailed studies of internal structure have provided the strongest anatomical evidence that Prototaxites is not a plant, but a fungus.

"Fran Hueber has contributed more to our understanding of Prototaxites than anyone else, living or dead," said Carol Hotton, also of the National Museum of Natural History. "He built up a convincing case based on the internal structure of the beast that it was a giant fungus, but agonized over the fact that he was never able to find a smoking gun in the form of reproductive structures that would convince the world that it was indeed a fungus," Hotton said.

Prototaxites lived worldwide from approximately 420 million to 350 million years ago. During this period, which spans part of the Silurian and Devonian periods of geologic time, terrestrial Earth looked quite alien in comparison to the modern world.

Simple vascular plants, the ancestors of the familiar conifers, ferns and flowering plants of today, began to diversify on land during the Devonian Period. "Initially, they're just stems. They don't have roots. They don't have leaves. They don't have anything like that," Boyce said.

Millipedes, wingless insects and worms were among the other organisms making a living on land by then, but no backboned animals had yet evolved out of the oceans. "That world was a very strange place," Boyce said.

Although vascular plants had established themselves on land 40 million years before the appearance of Prototaxites, the tallest among them stood no more than a couple feet high. By the end of the Devonian, approximately 345 million years ago, large trees, ferns, seeds, leaves and roots had all evolved. "They're all there. They just exploded over this one time period," Boyce said.

Canadian paleontologist Charles Dawson published the first research on Prototaxites in 1859, based on specimens found along the shores of Gaspé Bay in Quebec, Canada. Hueber pored through Dawson's field notebooks, written "in a completely illegible scrawl," Hotton said.

"Fran spent months deciphering them for clues about the localities where specimens had been collected, how Dawson interpreted them and other information that helped understand this humongous fungus," she said.

Hueber also traveled to Canada, Australia and Saudi Arabia to collect specimens. He tediously sliced them into hundreds of thin sections and made thousands of images taken through microscopes to determine the organism's identity.

Now Boyce, Hotton and their colleagues have produced independent evidence that supports Hueber's case. The team did so by analyzing two varieties--isotopes--of carbon contained in Prototaxites and the plants that lived in the same environment approximately 400 million years ago.

The metabolism of plants is limited by photosynthesis. Deriving their energy from the sun and their carbon from carbon dioxide in the air, any given type of plant will typically contain a similar ratio of carbon-12 to carbon-13 as another plant of the same type. "But if you're an animal, you will look like whatever you eat," Boyce said. And Prototaxites displayed a much wider variation in its ratio of carbon-12 to carbon-13 content than would be expected in any plant.

Geological processes can alter the isotopic composition of fossils, but Boyce and his colleagues conducted tests to verify that the carbon isotopic composition of the specimens they analyzed stemmed from organic rather than geologic factors.

As for why these bizarre organisms grew so large, "I've wondered whether it enabled Prototaxites to distribute its spores widely, allowing it to occupy suitable marshy habitats that may have been patchily distributed on the landscape," Hotton said.

The relatively simple Devonian ecosystems certainly seemed to contain nothing to prevent them from growing slowly for a long time. Plant-eating animals had not yet evolved, Boyce said. But even if Prototaxites hadn't been eaten by the dinosaurs and elephants that came much later, they probably grew too slowly to rebuild from regular disturbances of any kind, Boyce said.

"It's hard to imagine these things surviving in the modern world," he said.

Co-authoring the Geology paper with Boyce, Hotton and Hueber himself were Marilyn Fogel, George Cody and Robert Hazen of the Carnegie Institution of Washington, and Andrew Knoll of Harvard University. Their work was funded by NASA's Astrobiology Institute and by the American Chemical Society Petroleum Fund.


Story Source:

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


Cite This Page:

University of Chicago. "Prehistoric Mystery Organism Verified As Giant Fungus." ScienceDaily. ScienceDaily, 24 April 2007. <www.sciencedaily.com/releases/2007/04/070423080454.htm>.
University of Chicago. (2007, April 24). Prehistoric Mystery Organism Verified As Giant Fungus. ScienceDaily. Retrieved October 20, 2014 from www.sciencedaily.com/releases/2007/04/070423080454.htm
University of Chicago. "Prehistoric Mystery Organism Verified As Giant Fungus." ScienceDaily. www.sciencedaily.com/releases/2007/04/070423080454.htm (accessed October 20, 2014).

Share This



More Plants & Animals News

Monday, October 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Rare Lion Cubs Make Debut at Belgrade Zoo

Raw: Rare Lion Cubs Make Debut at Belgrade Zoo

AP (Oct. 17, 2014) — Two white lion cubs were born in Belgrade zoo three weeks ago. White lions are a rare mutation of a species found in South Africa and some cultures consider them divine. (Oct. 17) Video provided by AP
Powered by NewsLook.com
The Best Foods To Boost Your Mood

The Best Foods To Boost Your Mood

Buzz60 (Oct. 17, 2014) — Feeling down? Reach for the refrigerator, not the medicine cabinet! TC Newman (@PurpleTCNewman) shares some of the best foods to boost your mood. Video provided by Buzz60
Powered by NewsLook.com
Sweet Times for Hard Cider Makers

Sweet Times for Hard Cider Makers

AP (Oct. 16, 2014) — With hard cider making a hardcore comeback across the country, craft makers are trying to keep up with demand and apple growers are tapping a juicy new revenue stream. (Oct. 16) Video provided by AP
Powered by NewsLook.com
Meet Garfi the Angry Cat

Meet Garfi the Angry Cat

Buzz60 (Oct. 16, 2014) — Garfi is one frowny, feisty feline - downright angry! Ko Im (@koimtv) introduces us to the latest animal celebrity taking over the Internet. You can follow more of Garfi's adventures on Twitter (@MeetGarfi) and Facebook (Garfi). Video provided by Buzz60
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