Free Newsletters - Space - Defense - Environment - Energy - Solar - Nuclear
..
. 24/7 Space News .




EARLY EARTH
Counting calories in the fossil record
by Ker Than Stanford News
Stanford CA (SPX) Apr 08, 2014


Jonathan Payne holds fossil brachiopods that are more than 400 million years old. In the foreground are fossilized bivalves, a group that includes clams, mussels, and oysters. Image courtesy John Todd.

The shells of clams, oysters, mussels and other "bivalve" organisms litter nearly every shoreline around the world today. Shells also strewed the beaches of ancient Earth, but most of them belonged to very different kinds of creatures. Called brachiopods, these marine animals superficially resembled bivalves, but the two groups are only distantly related.

Starting about 250 million years ago, at the end of the Permian period, brachiopod groups disappeared in large numbers, along with 90 percent of the planet's species. Today, only a few groups, or genera, of brachiopods remain. "Most people won't be familiar with brachiopods. They're pretty rare in the modern ocean," said Jonathan Payne, a paleobiologist at Stanford University.

Meanwhile, bivalves flourished, diversifying into a staggering variety of shapes and sizes, and spread from marine to freshwater habitats. "After the end-Permian mass extinction, we find far fewer brachiopods and a lot more bivalves," said Payne, who is an associate professor in the Department of Geological and Environmental Sciences.

Why one group of shelled animals thrived while the other barely survived is one of the great mysteries in paleontology. A popular theory, based on diversity and abundance data from the fossil record for the two groups, is that bivalves simply outcompeted brachiopods. But a new study by Payne and other researchers that looks at the issue from an energy standpoint paints a different picture. Their findings, published online on March 26 in the journal Proceedings of the Royal Society B, show that, despite being fewer in number, ancient bivalves were already consuming as much food as brachiopods, and that modern bivalves consume vastly more.

"Brachiopods and bivalves used about same amount of food during Paleozoic, but bivalve food intake has increased by a factor of 100 since then," Payne said. "There's no way that increase is the result of bivalves simply displacing brachiopods. Even if bivalves had entirely supplanted brachiopods, their metabolism would have only doubled."

Payne and his collaborators reached their conclusions after conducting a comprehensive search of scientific literature and recording the body sizes of more than 6,000 ancient and modern genera of bivalves and brachiopods. Some of the fossils dated back to the Cambrian era, more than 500 million years ago. Five undergraduate students and high school interns spent an entire summer on the task.

Fossil records like the one used in the current study can also provide clues about how the biological makeup of the modern ocean evolved, Payne said. "If scientists want to know how evolution works, one of the best ways is to study changes in animal shape over Earth's history," he added. "By moving from form to function as we have done in this study, fossils give us a very direct way of comparing how ancient ecosystems worked compared to their modern counterparts."

From body size to metabolic rate
Once the body sizes of the different genera were known, the team was ready to estimate each one's metabolic rate. To do this, they used available data about the ratio between shell size and living, or "soft," tissue in modern bivalves and brachiopods to calculate the soft tissue amounts, and by extension the metabolic rates, of the extinct genera.

The results of their study showed that like their modern descendants, ancient brachiopods possessed relatively little soft tissue and would have had low metabolic rates compared to ancient bivalves. "It turns out that even though brachiopod and bivalve shells are about the same size, if you open up a brachiopod shell, there's a lot less meat inside," Payne said. "That's one reason that we eat bivalves, and not brachiopods. There also aren't there many brachiopods around, and some of them may be toxic to humans."

The new finding indicates that, from a metabolic standpoint at least, brachiopods didn't dominate the Paleozoic. At best, they split their ocean kingdom with bivalves. "Our study is unique in that it provides a deep time perspective of how life arose, and in this case declined as well, because of how these two group differentially use energy," said study coauthor Craig McClain, an oceanographer at the National Evolutionary Synthesis Center (NESCent) in Durham, NC. "Today's ocean reflects these evolutionary stories of the past. We can look at the modern oceans and see the end of the story-lots of bivalves and few brachiopods-but now we know more about the introduction and climax of the narrative."

Unlucky brachiopods
So if bivalves weren't responsible for the brachiopods fall from glory, then what was? It's likely, Payne said, that brachiopods were just unlucky. The evolutionary strategies that made them successful for hundreds of millions of years simply no longer worked or were even detrimental in the face of the environmental changes wrought by the End Permian extinction. "We think that about 250 million years ago, a series of large volcanic eruptions in Siberia ejected something on the order of 6 million kilometers of basalt rock. That's enough to cover all of Western Europe in a quarter-mile deep layer of basalt," Payne said.

When the scalding volcanic rock rained back to surface and penetrated the Earth's upper crust, it heated other rocks, causing them to release large amounts of gas, including the greenhouse gas carbon dioxide. This catastrophic chain reaction would have altered the chemistry of the oceans, increasing their acidity. Brachiopods would have been particularly hard hit by the change, Payne said. "Bivalves have gills and an active circulatory system, while brachiopods don't. That means that in general, bivalves are more effective at regulating their internal chemistries relative to the external environment."

Bivalves would have also been in a better position to take advantage of the new food sources that became available as life recovered from the mass extinction event. More creatures were becoming mobile, and brachiopods, which are largely stationary and filter feed on floating organic debris, would have been less able to capitalize on this shift. Meanwhile, bivalves such as clams were becoming more proficient at moving around by quickly opening and closing their shells or using their muscular foot to burrow. Increased mobility gave bivalves an edge not only over brachiopods, but likely other organisms as well, such as microbes. "What we see is that more mobile organisms tend to be better in the post-Paleozoic," Payne said.

The new findings cast the fate of the two groups in a new light: Bivalves didn't outcompete brachiopods by getting better at obtaining the food sources that the two groups shared. Rather, their physiological differences enabled them to branch out and take advantage of other food resources in ways that brachiopods simply couldn't follow.

.


Related Links
School of Earth Sciences
Explore The Early Earth at TerraDaily.com






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News





EARLY EARTH
Ancient shrimp had advanced cardiovascular system
Tucson (UPI) Apr 7, 2013
A group of international scientists have discovered the earliest example of an advanced cardiovascular system. The well-formed heart and blood vessels were found inside the body of a 520-million-year-old shrimp-like species. "This is the first preserved vascular system that we know of," said Nicholas Strausfeld, a neuroscience professor at the University of Arizona's Department of Neuro ... read more


EARLY EARTH
Misleading mineral may have resulted in overestimate of water in moon

Scientists date Moon at 4.470 billion years

Unique camera from NASA's moon missions sold at auction

Expeditions to the Moon: beware of meteorites

EARLY EARTH
Health risks of Mars mission would exceed NASA limits

Mars and Earth move closer together this month

The Opposition of Mars

Mars yard ready for Red Planet rover

EARLY EARTH
China, Asia-Pacific, will power world tourism: survey

Using ethic frameworks for decisions about health standards on long duration spaceflights

NASA suspends Russia ties, except on space station

NASA Marks Major Milestone for Spaceport of the Future

EARLY EARTH
China launches experimental satellite

Tiangong's New Mission

"Space Odyssey": China's aspiration in future space exploration

China to launch first "space shuttle bus" this year

EARLY EARTH
Soyuz Docking Delayed Till Thursday as Station Crew Adjusts Schedule

US, Russian astronauts take new trajectory to dock the ISS

Software glitch most probable cause of Soyuz TMA-12 taking two day approach

Russian spacecraft brings three-man crew to ISS after two-day delay

EARLY EARTH
EUTELSAT 3B Mission Status Update

Soyuz ready for Sentinel-1A satellite launch

Boeing wins contract to design DARPA Airborne Satellite Launch

Arianespace's seventh Soyuz mission from French Guiana is readied for liftoff next week

EARLY EARTH
Lick's Automated Planet Finder: First robotic telescope for planet hunters

Space Sunflower May Help Snap Pictures of Planets

NRL Researchers Detect Water Around a Hot Jupiter

UK joins the planet hunt with Europe's PLATO mission

EARLY EARTH
Materials and electronics that dissolve when triggered

Chemists develop gold coating that dims glare

Math modeling integral to synthetic biology research

World's oldest weather report could revise Bronze Age chronology




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.