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

    Chechen Suspected in Istanbul Attack, but Questions Remain

    Turkish sources say North Caucasus militants involved in bombing at Ataturk airport, but name of at least one alleged attacker raises doubts

    With Johnson Out, Can a New ‘Margaret Thatcher’ Save Britain?

    Contest to replace David Cameron as Britain’s prime minister started in earnest Thursday with top candidates outlining strategy to deal with Brexit fallout

    US Finds Progress Slow Against Human Trafficking in Africa

    Africa continues to be a major source and destination for human trafficking of all kinds -- from forced labor to sexual slavery, says State Department report

    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.
    Clinton Leads Trump, But Many Voters Don't Like Eitheri
    X
    Jim Malone
    June 29, 2016 6:16 PM
    In the U.S. presidential race, most recent polls show Democrat Hillary Clinton with a steady lead over Republican Donald Trump as both presumptive party nominees prepare for their party conventions next month. Trump’s disapproval ratings have risen in some recent surveys, but Clinton also suffers from high negative ratings, suggesting both candidates have a lot of work to do to improve their images before the November election. VOA National correspondent Jim Malone has more from Washington.
    Video

    Video Clinton Leads Trump, But Many Voters Don't Like Either

    In the U.S. presidential race, most recent polls show Democrat Hillary Clinton with a steady lead over Republican Donald Trump as both presumptive party nominees prepare for their party conventions next month. Trump’s disapproval ratings have risen in some recent surveys, but Clinton also suffers from high negative ratings, suggesting both candidates have a lot of work to do to improve their images before the November election. VOA National correspondent Jim Malone has more from Washington.
    Video

    Video Slow Rebuilding Amid Boko Haram Destruction in Nigeria’s Northeast

    Military operations have chased Boko Haram out of towns and cities in Nigeria’s northeast since early last year. But it is only recently that people have begun returning to their homes in Adamawa state, near the border with Cameroon, to try to rebuild their lives. For VOA, Chris Stein traveled to the area and has this report.
    Video

    Video New US Ambassador to Somalia Faces Heavy Challenges

    The new U.S. envoy to Somalia, who was sworn into office Monday, will be the first American ambassador to that nation in 25 years. He will take up his post as Somalia faces a number of crucial issues, including insecurity, an upcoming election, and the potential closure of the Dadaab refugee camp in Kenya. VOA’s Jill Craig asked Somalis living in Kenya’s capital city Nairobi how they feel about the U.S. finally installing a new ambassador.
    Video

    Video At National Zoo, Captivating Animal Sculptures Illustrate Tragedy of Ocean Pollution

    The National Zoo in Washington, D.C., is home to about 1,800 animals, representing 300 species. But throughout the summer, visitors can also see other kinds of creatures there. They are larger-than-life animal sculptures that speak volumes about a global issue — the massive plastic pollution in our oceans. VOA's June Soh takes us to the zoo's special exhibit, called Washed Ashore: Art to Save the Sea.
    Video

    Video Baghdad Bikers Defy War with a Roar

    Baghdad is a city of contradictions. War is a constant. Explosions and kidnappings are part of daily life. But the Iraqi capital remains a thriving city, even if a little beat up. VOA's Sharon Behn reports on how some in Baghdad are defying the stereotype of a nation at war by pursuing a lifestyle known for its iconic symbols of rebellion: motorbikes, leather jackets and roaring engines.
    Video

    Video Melting Pot of Immigrants Working to Restore US Capitol Dome

    The American Iron Works company is one of the firms working to renovate the iconic U.S. Capitol Dome. The company employs immigrants of many different cultural and national backgrounds. VOA’s Arman Tarjimanyan has more.
    Video

    Video Testing Bamboo as Building Material

    For thousands of years various species of bamboo - one of the world's most versatile plants - have been used for diverse purposes ranging from food and medicine to textiles and construction. But its use on a large scale is hampered because it's not manufactured to specific standards but grown in the ground. A University of Pittsburgh professor is on track to changing that. VOA’s George Putic reports.
    Video

    Video Orphanage in Iraqi City Houses Kids Who Lost their Parents to Attacks by IS

    An orphanage in Iraqi Kurdistan has become home to scores of Yazidi children who lost their parents after Islamic State militants took over Sinjar in Iraq’s Nineveh Province in 2014. Iraqi Kurdish forces backed by the U.S. airstrikes have since recaptured Sinjar but the need for the care provided by the orphanage continues. VOA’s Kawa Omar filed this report narrated by Rob Raffaele.
    Video

    Video Re-Opening Old Wounds in a Bullet-Riddled Cultural Landmark

    A cultural landmark before Lebanon’s civil war transformed it into a nest of snipers, Beirut’s ‘Yellow House’ is once again set to play a crucial role in the city.  Built in a neo-Ottoman style in the 1920s, in September it is set to be re-opened as a ‘memory museum’ - its bullet-riddled walls and bunkered positions overlooking the city’s notorious ‘Green Line’ maintained for posterity. John Owens reports from Beirut.
    Video

    Video Brexit Resounds in US Presidential Contest

    Britain’s decision to leave the European Union is resounding in America’s presidential race. As VOA’s Michael Bowman reports, Republican presumptive nominee Donald Trump sees Britain’s move as an affirmation of his campaign’s core messages, while Democrat Hillary Clinton sees the episode as further evidence that Trump is unfit to be president.
    Video

    Video NASA Juno Spacecraft, Nearing Jupiter, to Shed Light on Gas Giant

    After a five-year journey, the spacecraft Juno is nearing its destination, the giant planet Jupiter, where it will enter orbit and start sending data back July 4th. As Mike O'Sullivan reports from Pasadena, California, the craft will pierce the veil of Jupiter's dense cloud cover to reveal its mysteries.
    Video

    Video Orlando Shooting Changes Debate on Gun Control

    It’s been nearly two weeks since the largest mass shooting ever in the United States. Despite public calls for tighter gun control laws, Congress is at an impasse. Democratic lawmakers resorted to a 1960s civil rights tactic to portray their frustration. VOA’s Carolyn Presutti explains how the Orlando, Florida shooting is changing the debate.

    Special Report

    Adrift The Invisible African Diaspora