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

Multimedia Social Media Documenting, Not Driving, Hong Kong Protests

Unlike in Arab Spring uprisings, pro-democracy protesters in Hong Kong aren't relying on Twitter and Facebook to organize, but social media still plays a role More

Analysis: Occupy Central Not Exactly Hong Kong’s Tiananmen

VOA's former Hong Kong, Beijing correspondent compares and contrasts 1989 Tiananmen Square protest with what is now happening in Hong Kong More

Bambari Hospital a Lone Place of Help in Violence-Plagued CAR

Only establishment still functioning in CAR's second city is main hospital 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.
The Legacy of Jimmy Carter: The Preacher from Plainsi
X
October 01, 2014 10:45 AM
It is common in the United States to see tourists flock to sites associated with America's presidents. Some are privately owned and others are run by the National Park Service or the National Archives -- but most have helped draw business and people into the towns and cities where they are located. As VOA’s Kane Farabaugh reports, there is one particular presidential hometown that is unique in what it has to offer those who make the trip.
Video

Video The Legacy of Jimmy Carter: The Preacher from Plains

It is common in the United States to see tourists flock to sites associated with America's presidents. Some are privately owned and others are run by the National Park Service or the National Archives -- but most have helped draw business and people into the towns and cities where they are located. As VOA’s Kane Farabaugh reports, there is one particular presidential hometown that is unique in what it has to offer those who make the trip.
Video

Video Hong Kong Protests Draw New Supporters on National Holiday

On the 65th anniversary of the founding of Communist China, Hong Kong protesters are hoping to stage the largest pro-democracy demonstration since the 1989 Tiananmen protests. VOA's Brian Padden visited one of the protest sites mid-day, when the atmosphere was calm and where the supporters were enthusiastic about joining what they are calling the umbrella revolution.
Video

Video India's PM Continues First US Visit

India's prime minister is on his first visit to Washington, to strengthen political and economic ties between the world's oldest and the world biggest democracies. He came to the U.S. capital from New York, the first stop on his five-day visit to the country that denied him an entry visa in the past. From Washington, Zlatica Hoke reports Modi seemed most focused on attracting foreign investment and trade to increase job opportunities for his people.
Video

Video Malaysia Struggles to Stop People Joining Jihad

Malaysian authorities say militant groups like the so-called "Islamic State" have used social media to entice at least three dozen Malaysian Muslims to fight in what they call "jihad" in Syria and Iraq. As Mahi Ramkrishnan reports from Kuala Lumpur, counterterrorism police are deeply worried about what could happen when these militants return home.
Video

Video Could US Have Done More to Stop Rise of Islamic State?

President Obama says airstrikes against Islamic State militants in Syria will likely continue for some time because, in his words, "there is a cancer that has grown for too long." So what if President Obama had acted sooner in Syria to arm more-moderate opponents of both the Islamic State and the Syrian government? VOA State Department Correspondent Scott Stearns reports from the United Nations.
Video

Video Treasure Hunters Seek 'Hidden Treasure' in Central Kenya

Could a cave in a small village in central Kenya be the site of buried treasure? A rumor of riches, left behind by colonialists, has some residents dreaming of wealth, while others see it as a dangerous hoax. VOA's Gabe Joselow has the story.
Video

Video Ebola Patients Find No Treatment at Sierra Leone Holding Center

At a holding facility in Makeni, central Sierra Leone, dozens of sick people sit on the floor in an empty university building. They wait in filthy conditions. It's a 16-hour drive by ambulance to Kailahun Ebola treatment center. Adam Bailes was there and reports on what he says are some of the worst situations he has seen since the beginning of this Ebola outbreak. And he says it appears case numbers may already be far worse than authorities acknowledge.
Video

Video Identifying Bodies Found in Texas Border Region

Thousands of immigrants have died after crossing the border from Mexico into remote areas of the southwestern United States in recent years. Local officials in south Texas alone have found hundreds of unidentified bodies and buried them in mass graves in local cemeteries. Now an anthropologist and her students at Baylor University have been exhuming bodies and looking for clues to identify them. VOA’s Greg Flakus has more from Waco, Texas.
Colonel Steve ‘Spiros’ Pisanos left Greece and came to the U.S. to learn to fly. He flew fighters for the Allies in World War II, narrowly escaping death multiple times.Colonel Steve ‘Spiros’ Pisanos left Greece and came to the U.S. to learn to fly. He flew fighters for the Allies in World War II, narrowly escaping death multiple times.

AppleAndroid