Primates, like humans, are commonly believed to have originated in Africa. But Yaoming Hu, a vertebrate paleontologist at the American Museum of Natural History in New York, recently found the oldest known primate, named Teilhardina asiatica, in the 55-million-year-old red mudstone of southern China. The mouse-size creature’s relatively large braincase and short snout clearly mark it as a primate, says Hu, who made the discovery in collaboration with Xijun Ni and colleagues at the Chinese Academy of Sciences in Beijing.
The creature’s eyes were relatively small compared with those of other primates, which means it was probably active during the day. That comes as another surprise: Most primitive living primates are nocturnal, so paleontologists inferred that the common primate ancestor was too. “Now we have evidence that at least some early primates were diurnal and that the ancestor of primates was probably also diurnal,” Hu says.
Indirect evidence indicates the first primate may have arisen significantly earlier than 55 million years ago, so Teilhardina is probably not the end of the story. “It is almost impossible for us to know exactly where any one group of animals evolved because the fossil record is always very incomplete,” Hu says. Early primate remains are especially small and fragile. Hu’s next step is a trip back to China to search out more surprises.