News / Science & Technology

Scientist: Ancient Fish Shows Signs of Rear-Leg Development

Reuters
Fossils of an ancient fish species discovered in the Canadian Arctic show that hind legs evolved from fins some 375 million years ago, challenging a theory that they developed only after vertebrates took to land, according to research published this week.
 
The remains of the fish, the Tiktaalik roseae, were discovered in 2004 on southern Ellesmere Island in northern Canada by a team of scientists that included a now-deceased Harvard University professor, Farish Jenkins, according to the findings published in the Proceedings of the National Academy of Sciences, a scientific journal.
 
Researchers had initially focused only on specimens containing the front portion of the fish but subsequently discovered pelvises and partial pelvic fin material from the rear portion that were comparable to those of some early four-legged animals, with a ball-and-socket hip joint.
 
“This is an amazing pelvis, particularly the hip socket, which is very different from anything that we knew of in the lineage leading up to limbed vertebrates,” Ted Daeschler, associate curator of vertebrate zoology at Drexel University in Philadelphia and a co-author of the study, said in a statement.
 
The prevailing scientific understanding, Daeschler said, was based on “a 'front-wheel drive' idea that these animals were primarily using their front limbs for locomotion,” while hind limbs were small and not necessarily used for movement.
 
“It looks like this shift actually began to happen in fish, not in limbed animals,” Neil Shubin, a University of Chicago professor and co-author of the study, said in the statement. “It's reasonable to suppose with those big fin rays that Tiktaalik used its hind fins to swim like a paddle. But it's possible it could walk with them as well.”
 
The Tiktaalik roseae looked like a cross between a fish and a crocodile, with lobe fins, a broad flat head and sharp teeth, according to Drexel. It hunted in shallow freshwater environments and grew to a length of up to nine feet (2.7 meters).
 
It had gills, scales and fins, but also features associated with four-legged animals — a mobile neck, a robust ribcage and primitive lungs — the university said. Its large forefins had shoulders, elbows and partial wrists, allowing it to support itself on ground.
 
Such features make the fish one of the best-known transitional species between fish and land-dwelling tetrapods, or animals with two pairs of limbs, the university said.

You May Like

Lesotho Faces New Round of Violence, Political Crisis

Brutal killing of military officer has sent former leaders back into S. Africa where they're watching anxiously as regional officials head in to try to restore peace More

Video US Diplomat Expects Adoption of Bosnian Massacre Anniversary Resolution

Samantha Power says there's broad consensus about killings in Bosnia's war, but Russia calls resolution 'divisive,' backs UN countermeasure More

UN Report Exposes Widespread Boko Haram Atrocities

Damning report graphically details pattern of vicious, widespread atrocities committed by Islamist militants More

This forum has been closed.
Comments
     
There are no comments in this forum. Be first and add one

Featured Videos

Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
Olympics Construction Scars Sacred Korean Mountaini
X
July 02, 2015 4:10 AM
Environmentalists in South Korea are protesting a Winter Olympics construction project to build a ski slope through a 500-year-old protected forest. Brian Padden reports that although there is strong national support for hosting the 2018 Pyeongchang Winter Olympics, there are growing public concerns over the costs and possible ecological damage at the revered mountain.
Video

Video Olympics Construction Scars Sacred Korean Mountain

Environmentalists in South Korea are protesting a Winter Olympics construction project to build a ski slope through a 500-year-old protected forest. Brian Padden reports that although there is strong national support for hosting the 2018 Pyeongchang Winter Olympics, there are growing public concerns over the costs and possible ecological damage at the revered mountain.
Video

Video Xenophobia Victims in South Africa Flee Violence, Then Return

Many Malawians fled South Africa early this year after xenophobic attacks on African immigrants. But many quickly found life was no better at home and have returned to South Africa – often illegally and without jobs, and facing the tough task of having to start over. Lameck Masina and Anita Powell file from Johannesburg.
Video

Video Family of American Marine Calls for Release From Iranian Prison

As the crowd of journalists covering the Iran talks swells, so too do the opportunities for media coverage.  Hoping to catch the attention of high-level diplomats, the family of American-Iranian marine Amir Hekmati is in Vienna, pleading for his release from an Iranian prison after nearly 4 years.  VOA’s Heather Murdock reports from Vienna.
Video

Video UK Holds Terror Drill as MPs Mull Tunisia Response

After pledging a tough response to last Friday’s terror attack in Tunisia, which came just days before the 10th anniversary of the bomb attacks on London’s transport network, British security services are shifting their focus to overseas counter-terror operations. VOA's Henry Ridgwell has more.
Video

Video Obama on Cuba: This is What Change Looks Like

President Barack Obama says the United States will soon reopen its embassy in Cuba for the first time since 1961, ending a half-century of isolation. VOA White House correspondent Luis Ramirez reports.
Video

Video Hate Groups Spread Influence Via Internet

Hate groups of various kinds are using the Internet for propaganda and recruitment, and a Jewish human rights organization that monitors these groups, the Simon Wiesenthal Center, says their influence is growing. The messages are different, but the calls to hatred or violence are similar. VOA's Mike O’Sullivan reports.
Video

Video US Silica Sand Mining Surge Worries Illinois Residents, Businesses

Increased domestic U.S. oil and gas production, thanks to advances known as “fracking,” has created a boom for other industries supporting that extraction. Demand for silica sand, used in fracking, could triple over the next five years. In the Midwest state of Illinois, people living near the mines are worried about how increased silica sand mining will affect their businesses and their health. VOA’s Kane Farabaugh has more in this first of a series of reports.
Video

Video Blind Somali Journalist Defies Odds in Mogadishu

Despite improving security in the last few years, Somalia remains one of the most dangerous countries to be a journalist – even more so for someone who cannot see. Abdulaziz Billow has the story of journalist Abdifatah Hassan Kalgacal, who has been reporting from the Somali capital for the last decade despite being blind.
Video

Video Texas Defies Same-Sex Marriage Ruling

Texas state officials have criticized the US Supreme Court decision giving same-sex couples the right to marry nationwide. The attorney general of Texas says last week's decision did not overrule constitutional "rights of religious liberty," and therefore officials performing wedding services can refuse to perform them for same-sex couples if it is against their religious beliefs. Zlatica Hoke reports on the controversy.
Video

Video Rabbi Hits Road to Heal Jewish-Muslim Relations in France

France is on high alert after last week's terrorist attack near the city Lyon, just six months after deadly Paris shootings. The attack have added new tensions to relations between French Jews and Muslims. France’s Jewish and Muslim communities also share a common heritage, though, and as far as one French rabbi is concerned, they are destined to be friends. From the Paris suburb of La Courneuve, Lisa Bryant reports about Rabbi Michel Serfaty and his friendship bus.
Video

Video Saudi Leaks Expose ‘Checkbook Diplomacy’ In Battle With Iran

Saudi Arabia’s willingness to wield its oil money on the global diplomatic stage appears to have been laid bare, after the website WikiLeaks published tens of thousands of leaked cables from Riyadh’s Ministry of Foreign Affairs. VOA's Henry Ridgwell reports.
Video

Video In Kenya, Police Said to Shoot First, Ask Questions Later

An organization that documents torture and extrajudicial killings says Kenyan police were responsible for 1,252 shooting deaths in five cities, including Nairobi, between 2009 and 2014, representing 67 percent of all gun deaths in the areas reviewed. Gabe Joselow has more from Nairobi.

VOA Blogs