A new fossil discovered in Tunisia represents the oldest known ancestor of modern-day sea cows, supporting the African origins of these marine mammals. The find is described in research published January 16 in the open access journal PLOS ONE by Julien Benoit and colleagues from the University of Science and Technology in Montpellier, France.
Some fossils of sea cow ancestors have been found in Jamaica, but the Tunisian fossil is more primitive and pre-dates these, revealing an older ancestor for sea cows that emerged at the same time as other modern mammals. Unlike whales and dolphins, the evolutionary origins of the sea cow family have been obscure.
They share an ancestor with elephants, and it is thought that their oldest relatives were terrestrial animals that gradually adapted to an aquatic life. The last common ancestor of the two species may have lived in freshwater swamps well before the time that the new species described in this study lived. Though this specimen may not have been the common link between modern day sea cows and elephants, the authors' analyses suggest that this new species lived in fresh water, not sea waters.
Citation: Benoit J, Adnet S, El Mabrouk E, Khayati H, Ben Haj Ali M, et al. (2013) Cranial Remain from Tunisia Provides New Clues for the Origin and Evolution of Sirenia (Mammalia, Afrotheria) in Africa. PLoS ONE 8(1): e54307. doi:10.1371/journal.pone.0054307
Financial Disclosure: This work has been conducted with the support of the Agence nationale de la recherche (ANR) (Conseil Europe´en de la Recherche (ERC) programme Palasiafrica (ANR-08-JCJC-0017-01). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing Interest Statement: The authors have declared that no competing interests exist.
PLEASE LINK TO THE SCIENTIFIC ARTICLE IN ONLINE VERSIONS OF YOUR REPORT (URL goes live after the embargo ends): http://dx.plos.org/10.1371/journal.pone.0054307