June 4, 2012
New Evidence Points To Asia As Source Of Earliest Anthropoid Primates
Brett Smith for redOrbit.com
The discovery of a new fossilized primate from Myanmar, Afrasia djijidae, illuminates a critical step in the evolution of early primates; according to a scientific paper describing the discovery that appears today in the Proceedings of the National Academy of Sciences.
An international research team located four teeth from the 37 million-year-old Afrasia in central Myanmar not far from their 2009 discovery of Ganlea megacania, another fossilized primate that cemented the theory of early primate´s existence in Asia.
“The fossils were all found in central Myanmar, west of the Irrawaddy River,” reported Christopher Beard, Carnegie Museum of Natural History paleontologist and member of the discovery team that also included researchers from Myanmar, Thailand, and France. “This area is subject to annual monsoon rains, but it remains very dry for the rest of the year. As a result, erosion is high enough that ℠badland´ hills develop, which are the areas where it is easiest to find fossils.”
“(Afrasia and Ganlea) were found about 5 miles apart as the crow flies, but the roads in this part of Myanmar are very difficult, so it is not easy to travel from one site to the other,” Beard told redOrbit via email.
Afrasia closely resembles another early anthropoid, Afrotarsius libycus, recently discovered in a Libyan section of the Sahara Desert. The close similarity and relative age of the two primates indicates that early anthropoids migrated to Africa only shortly before the time when these animals lived. This migration likely set the stage for future primate development.
“We think that these early anthropoids probably made their way to Africa by accident,” Beard wrote.
“Somehow, they had to cross an ancient sea (called the Tethys Sea) that separated Africa from Eurasia at that time. They probably were passive ℠castaways´ on ℠floating islands´ of earth and vegetation that were eroded from the banks of large rivers in Asia during heavy storms or cyclones. These floating islands would have washed out to sea, where they would have functioned like sail boats with a "crew" of little tiny monkeys.”
Based on decades of evidence and theories, scientists thought that anthropoid evolution was rooted in Africa. However, recent discoveries in China, Myanmar, and other Asian countries have rapidly shifted scientific opinion about where this group of human ancestors first evolved.
"For years we thought the African fossil record was simply bad," said team leader Jean-Jacques Jaeger of the University of Poitiers in France. “The fact that such similar anthropoids lived at the same time in Myanmar and Libya suggests that the gap in early African anthropoid evolution is actually real. Anthropoids didn't arrive in Africa until right before we find their fossils in Libya."
Beard expects his team to continue to flesh out the connection between early anthropoids living in Asia and Africa.
“We want to continue our search for more fossils in both Myanmar and Libya. We need to find better fossil specimens so we can determine more about the paleobiology and lifestyle of these distant human ancestors. We also want to find out more details about exactly how and when they made their way to Africa from Asia. Finally, we want to trace their evolutionary history both forward in time (towards us) and backward in time (towards more primitive fossil anthropoids known from Asia).”