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Primeval primate. The newly discovered skull of Teilhardina asiatica (top) may shed light on primate origins.

Earliest Primate Discovered in China

A primate skull found in China challenges the notion that the earliest primates were nocturnal and lends support to the theory that modern primates originated in Asia. The 55-million-year-old skull, not much bigger than a gumball, is in such good shape that nearly all its teeth are intact. It is the most complete skull ever found of a euprimate, the first mammals that shared characteristics such as forward-facing eyes and a large braincase with modern primates, including lemurs, apes, and humans.

Bits and pieces of euprimates, all dating to about 55 million years ago, have been found in Europe and North America. The discovery of a euprimate in Asia means that "modern" primates were already widespread by then and that their common ancestor must have evolved even earlier. But when and where is up for debate. Some scientists place the earliest primate in Africa 65 million years ago when the Age of Mammals began. But genetic studies of living primates bump that date back even further, to as much as 85 million years ago.

The new find doesn't clear up the "when," but it broadens the "where," drawing attention to Asia, which is nowadays home to many primitive mammals such as the tree shrew and flying lemur. A team of paleontologists led by Xijun Ni of the Chinese Academy of Sciences in Beijing unearthed the new euprimate species, Teilhardina asiatica, from China's Hunan Province. They describe the mouse-sized primate in the 1 January issue of Nature and argue that its relatively small eyes indicate that it hunted during the day. This goes against the popular notion that our early ancestors were nocturnal, with large round eyes for seeing in the dark.

Primatologist Robert Martin of the Field Museum in Chicago takes issue with the authors' conclusion that T. asiatica liked daylight best. He notes that some primate species were omitted in the comparative analysis, and he points out that that the skull has a large opening on the snout for the nerve connected to the whiskers, which tend to be more developed in nocturnal mammals. But paleontologist Chris Beard of the Carnegie Museum of Natural History in Pittsburgh, Pennsylvania, says the new discovery that the earliest modern primates had small eyes turns the traditional view of primate evolution "on its head."

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