News / Science & Technology

Sharks More Evolved than Previously Thought

A Sand Tiger Shark swims in its aquarium, File November 9, 2010.
A Sand Tiger Shark swims in its aquarium, File November 9, 2010.

Related Articles

Mount Everest Climb Exposes Diabetes Mechanism - Study

Using world’s highest mountain as outdoor laboratory, British researchers get clues on what triggers adult onset form of disease

NASA Says Human Landing on Mars on Track for 2030s

US space agency likens steps to get to Red Planet to building blocks that put men on the Moon

Saturn May Be Creating a New Moon

Photo sent by spacecraft shows bright protrusion on edge of one of planet's outer rings, which could be gravitational disturbance caused by small moon
VOA News
Sharks may not be “living fossils,” as was once thought.

Researchers say analysis of a 325-million-year-old shark skeleton could “profoundly affect our understanding of evolutionary history.”
 
Using a fossil of the newly discovered Ozarcus mapesae specimen, scientists at the American Museum of Natural History in New York had a unique chance to study a fossilized skeleton preserved in 3D, according to the researchers.

Since shark skeletons are made of cartilage, fossilized specimens are usually flattened, making it difficult to understand how they were structured.

“Sharks are traditionally thought to be one of the most primitive surviving jawed vertebrates. And most textbooks in schools today say that the internal jaw structures of modern sharks should look very similar to those in primitive shark-like fishes,” said Alan Pradel in a statement

“But we’ve found that’s not the case. The modern shark condition is very specialized, very derived, and not primitive,” said Pradel, a postdoctoral researcher at the museum and the lead author of the study.

According to the researchers, fish heads, including sharks, “are segmented into the jaws and a series of arches that support the jaw and the gills.” The arches were thought to have developed into jaws in early in evolution.

“This beautiful fossil offers one of the first complete looks at all of the gill arches and
associated structures in an early shark. There are other shark fossils like this in existence, but this is the oldest one in which you can see everything,” said John Maisey, a curator in the Museum’s Division of Paleontology and one of the authors on the study.

“There’s enough depth in this fossil to allow us to scan it and digitally dissect out the cartilage skeleton,” he said.
The exceptionally well-preserved fossil of Ozarcus mapesae from two different lateral views. The scale bar is 10 millimeters. (©AMNH/F. Ippolito)The exceptionally well-preserved fossil of Ozarcus mapesae from two different lateral views. The scale bar is 10 millimeters. (©AMNH/F. Ippolito)
x
The exceptionally well-preserved fossil of Ozarcus mapesae from two different lateral views. The scale bar is 10 millimeters. (©AMNH/F. Ippolito)
The exceptionally well-preserved fossil of Ozarcus mapesae from two different lateral views. The scale bar is 10 millimeters. (©AMNH/F. Ippolito)
Using x-rays, scientists were able to view the shape and organization of the arches.

“We discovered that the arrangement of the arches is not like anything you’d see in a modern shark or shark-like fish,” said Pradel. “Instead, the arrangement is fundamentally the same as bony fishes.”

Scientists said that while sharks have been around for 420 million years, it would not be unexpected to see some evolution in their arch and jaw structures, leading to the conclusion that they may not be quite the window to the past as previously thought.

“Bony fishes might have more to tell us about our first jawed ancestors than do living sharks,” Maisey said.

The Ozarcus mapesae fossil was found in Arkansas, which was once home to an ocean basin that housed a diverse set of ancient marine life.

The research is published this week in the journal Nature.

You May Like

UN Watchdog Urges Israel to Probe Possible Gaza War Crimes

More than 2,100 Palestinians, most of them civilians, were killed in a 51-day war in Gaza, along with 67 Israeli soldiers and six civilians in Israel More

New Kenyan 'Thin SIMs' Poised to Transform African Mobile Money

Equity's new technology is approved in African nation for one-year trial, though industry leader Safaricom says thin SIMs could lead to data theft and fraud More

Solar's Future Looks Brighter

New technology and dropping prices are contributing to a surge in solar power More

This forum has been closed.
Comment Sorting
Comments
     
by: Nathann from: The puget sound region.
April 17, 2014 2:32 PM
Yet again all they have are similarities between species

Featured Videos

Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
Talks to Resume on Winter Gas for Ukrainei
X
Al Pessin
October 25, 2014 4:21 PM
Ukrainian and Russian officials will meet again next week in an effort to settle their dispute over natural gas supplies that threatens to leave Ukraine short of heating fuel for the coming winter. VOA’s Al Pessin reports from London the dispute is complex, and has both economic and geopolitical dimensions.
Video

Video Talks to Resume on Winter Gas for Ukraine

Ukrainian and Russian officials will meet again next week in an effort to settle their dispute over natural gas supplies that threatens to leave Ukraine short of heating fuel for the coming winter. VOA’s Al Pessin reports from London the dispute is complex, and has both economic and geopolitical dimensions.
Video

Video Smugglers Offer Cheap Passage From Turkey to Syria

Smugglers in Turkey offer a relatively cheap passage across the border into Syria. Ankara has stepped up efforts to stem the flow of foreign fighters who want to join Islamic State militants fighting for control of the Syrian border city of Kobani. But porous borders and border guards who can be bribed make illegal border crossings quite easy. Zlatica Hoke has more.
Video

Video China Political Meeting Seeks to Improve Rule of Law

China’s communist leaders will host a top level political meeting this week, called the Fourth Plenum, and for the first time in the party’s history, rule of law will be a key item on the agenda. Analysts and Chinese media reports say the meetings could see the approval of long-awaited measures aimed at giving courts more independence and include steps to enhance an already aggressive and high-reaching anti-corruption drive. VOA’s Bill Ide has more from Beijing.
Video

Video After Decades of Pressure, Luxembourg Drops Bank Secrecy Rules

European Union finance ministers have reached a breakthrough agreement that will make it more difficult for tax cheats to hide their money. The new legislation, which had been blocked for years by countries with a reputation as tax havens, was approved last week after Luxembourg and Austria agreed to lift their vetoes. But as Mil Arcega reports, it doesn’t mean tax cheats have run out of places to keep their money hidden.
Video

Video Kobani Refugees Welcome, Turkey Criticizes, US Airdrop

Residents of Kobani in northern Syria have welcomed the airdrop of weapons, ammunition and medicine to Kurdish militia who are resisting the seizure of their city by Islamic State militants. The Turkish government, however, has criticized the operation. VOA’s Scott Bobb reports from southeastern Turkey, across the border from Kobani.
Video

Video US ‘Death Cafes’ Put Focus on the Finale

In contemporary America, death usually is a topic to be avoided. But the growing “death café” movement encourages people to discuss their fears and desires about their final moments. VOA’s Jerome Socolovsky reports.
Video

Video Ebola Orphanage Opens in Sierra Leone

Sierra Leone's first Ebola orphanage has opened in the Kailahun district. Hundreds of children orphaned since the beginning of the Ebola outbreak face stigma and rejection with nobody to care for them. Adam Bailes reports for VOA about a new interim care center that's aimed at helping the growing number of children affected by Ebola.

All About America

AppleAndroid