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

    US Leaders Who Served in Vietnam War Look Back and Ahead

    In New York Times opinion piece, Secretary of State John Kerry, Senator John McCain and former Senator Bob Kerrey say as US strengthens relations with Vietnam, it is important to remember lessons learned from war

    Who Are US Allies in Fight Against Islamic State?

    There is little but opportunism keeping coalition together analysts warn — SDFs Arab militias are not united even among themselves, frequently squabble and don’t share Kurds' vision for post-Assad Syria

    Learning Foreign Language Helps US Soldiers Bridge Culture Gap

    Effective interaction with local populations part of everyday curriculum at Monterey, California, Defense Language Institute

    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.
    Vietnamese-American Youth Optimistic About Obama's Visit to Vietnami
    X
    Elizabeth Lee
    May 22, 2016 6:04 AM
    U.S. President Barack Obama's visit to Vietnam later this month comes at a time when Vietnam is seeking stronger ties with the United States. Many Vietnamese Americans, especially the younger generation, are optimistic Obama’s trip will help further reconciliation between the two former foes. Elizabeth Lee has more from the community called "Little Saigon" located south of Los Angeles.
    Video

    Video Vietnamese-American Youth Optimistic About Obama's Visit to Vietnam

    U.S. President Barack Obama's visit to Vietnam later this month comes at a time when Vietnam is seeking stronger ties with the United States. Many Vietnamese Americans, especially the younger generation, are optimistic Obama’s trip will help further reconciliation between the two former foes. Elizabeth Lee has more from the community called "Little Saigon" located south of Los Angeles.
    Video

    Video First-generation, Afghan-American Student Sets Sights on Basketball Glory

    Their parents are immigrants to the United States. They are kids who live between two worlds -- their parents' homeland and the U.S. For many of them, they feel most "American" at school. It can be tricky balancing both worlds. In this report, produced by Beth Mendelson, Arash Arabasadi tells us about one Afghan-American student who seems to be coping -- one shot at a time.
    Video

    Video Newest US Citizens, Writing the Next Great Chapter

    While universities across the United States honor their newest graduates this Friday, many immigrants in downtown Manhattan are celebrating, too. One hundred of them, representing 31 countries across four continents, graduated as U.S. citizens, joining the ranks of 680,000 others every year in New York and cities around the country.
    Video

    Video Vietnam Sees Strong Economic Growth Despite Incomplete Reforms

    Vietnam has transformed its communist economy to become one of the world's fastest-growing nations. While the reforms are incomplete, multinational corporations see a profitable future in Vietnam and have made major investments -- as VOA's Jim Randle reports.
    Video

    Video Qatar Denies World Cup Corruption

    The head of Qatar’s organizing committee for the 2022 World Cup insists his country's bid to host the soccer tournament was completely clean, despite the corruption scandals that have rocked the sport’s governing body, FIFA. Hassan Al-Thawadi also said new laws would offer protection to migrants working on World Cup construction projects. VOA's Henry Ridgwell reports.
    Video

    Video Infrastructure Funding Puts Cambodia on Front Line of International Politics

    When leaders of the world’s seven most developed economies meet in Japan next week, demands for infrastructure investment world wide will be high on the agenda. Japanese Prime Minister Shinzo Abe’s push for “quality infrastructure investment” throughout Asia has been widely viewed as a counter to the rise of Chinese investment flooding into region.
    Video

    Video Democrats Fear Party Unity a Casualty in Clinton-Sanders Battle

    Democratic presidential front-runner Hillary Clinton claimed a narrow victory in Tuesday's Kentucky primary even as rival Bernie Sanders won in Oregon. Tensions between the two campaigns are rising, prompting fears that the party will have a difficult time unifying to face the presumptive Republican nominee, Donald Trump. VOA national correspondent Jim Malone has more from Washington.
    Video

    Video Portrait of a Transgender Marriage: Husband and Wife Navigate New Roles

    As controversy continues in North Carolina over the use of public bathrooms by transgender individuals, personal struggles with gender identity that were once secret are now coming to light. VOA’s Tina Trinh explored the ramifications for one couple as part of trans.formation, a series of stories on transgender issues.
    Video

    Video Amerikan Hero Flips Stereotype of Middle Eastern Character

    An Iranian American comedian is hoping to connect with American audiences through a film that inverts some of Hollywood's stereotypes about Middle Eastern characters. Sama Dizayee reports.
    Video

    Video Budding Young Inventors Tackle City's Problems with 3-D Printing

    Every city has problems, and local officials and politicians are often frustrated by their inability to solve them. But surprising solutions can come from unexpected places. Students in Baltimore. Maryland, took up the challenge to solve problems they identified in their city, and came up with projects and products to make a difference. VOA's June Soh has more on a digital fabrication competition primarily focused on 3-D design and printing. Carol Pearson narrates.

    Special Report

    Adrift The Invisible African Diaspora