up on whale evolution
In the deserts of Pakistan, two independent research teams unearthed fossils that elucidate the evolutionary history of whales. Both sets of bones suggest that the whale, or Cetacea, ancestor was a land-dwelling artiodactyl like a sheep, camel or hippopotamus, and lived about 50 million years ago.
Recent molecular analyses place cetaceans as close relatives of the artiodactyls and, more specifically, as the sister group, or most closely related species to the hippo. Without fossils to back up this classification, though, paleontologists labeledcetaceans the sister taxon of a different group of mammals - extinct, hoofed, land-dwelling carnivores called mesonychians.
Phillip Gingerich of the Department of Geological Sciences at the University of Michigan, and his colleagues report their findings in Science online on Sept. 19 and in journal form on the Sept. 21. They describe their discovery of two 47-million-year-old partial whale skeletons in the Balochistan Province of Pakistan.
The skeletons include anklebones that are characteristic of artiodactyls, which gave the authors clear evidence that modern whales descended from artiodactyls, not mesonychians. Gingerich also suggests that hippos may indeed be modern whales' closest relative.
[Hans Thewissen examines rock specimens containing 47-million-year-old fossils of whale ancestors. He and his research team brought these back from a fossil dig in Pakistan this past summer. Courtesy of www.neoucom.edu/Depts/Anat/publ.html.]
Hans Thewissen of Northeastern Ohio Universities College of Medicine and colleagues report their findings in the Sept. 20 Nature. The partial skulls and anklebones of early cetaceans they uncovered in Pakistan suggest that early cetaceans were fully terrestrial. Thewissen and his colleagues also compared the skeletal features of these fossils to 27 other taxa, finding a close kinship between ancient cetaceans and artiodactyls. Contrary to molecular data, however, their analysis showed that cetaceans are not a hippo sister group.
On Sept. 17 and 18, the president's 16-member Commission on Ocean Policy held its organizational meeting in Washington, D.C. At this first gathering, commission members chose their chairman, James Watkins, a retired Navy admiral and president emeritus of the Consortium for Oceanographic Research and Education.
The Commission on Ocean Policy, established through the Oceans Act of 2000, will conduct a review of ocean-related issues and make recommendations to President Bush and Congress for a comprehensive policy on the oceans and Great Lakes. The review spans 18 months and includes six public hearings and the submittal of a final report to the president.
Not since the Stratton Commission, which created a comprehensive set of policy recommendations in 1969, has the federal government sought a comprehensive ocean policy. The Stratton Commission's recommendations established the National Oceanic and Atmospheric Administration and laid the groundwork for significant fisheries and coastal management legislation, including the National Marine Sanctuaries Act.
"They really do have a daunting task," says Ellen Prager, assistant dean at the University of Miami's Rosenstiel School of Marine and Atmospheric Science, of the recently appointed members. The commission will help policy-makers address issues ranging from marine pollution and climate change, to fisheries and coastal management.
The Commission on Ocean Policy meets again Nov. 13 and 14 in Washington, D.C. For more details, visit www.oceancommission.gov.
Lisa M. Pinsker