Research
Stony Brook University Researcher Confirms First Cranial Specimen Of Extinct Tarsier

STONY BROOK, N.Y., March 13, 2006—A Stony Brook University researcher and his colleagues have identified the first cranial specimen of an extinct tarsier from a 45 million-year-old site in China, a discovery that unlocks one of the mysteries of primate evolution. The discovery, reported in the journal Proceedings of the National Academy of Science, indicates that living tarsiers look virtually the same as their distant ancestors, in contrast to the dramatic changes undergone by most other primate lineages, such as humans, over a much shorter period of time.

Tarsiers are the closest relatives of anthropoids—humans, apes, and monkeys—but little has been known about their evolution until recent years. The specimen reported in the journal was found in southern Jiangsu Province in China by K. Christopher Beard of the Carnegie Museum of Natural History in Pittsburgh and analyzed in collaboration with James B. Rossie, a Professor of Anthropology at Stony Brook University, and Xijun Ni of the Institute of Vertebrate Paleontology and Paleoanthropology at the Chinese Academy of Sciences.

“The enormous eyes of tarsiers, each of which is larger than its whole brain, are an adaptation related to their nocturnal lifestyles,” Rossie said. “We knew that tarsiers became nocturnal at some point in their long evolutionary history, but we didn’t know how early this might have happened. The new fossil tells us that it had occurred by at least 45 million years ago.”

The facial fragment, which is classified as Tarsius ecocaenus, is virtually identical to the corresponding anatomy in living tarsiers and differs substantially from that of early anthropoids. The new specimen indicates that tarsiers already possessed their greatly enlarged eyes by the time they are first documented in the fossil record 45 million years ago. This shows that their distinctive ecological niche was not a recent development.

Small and pinkish, tarsiers are distinguished by their enormous eyes and long feet. Their feet have extremely elongated tarsus bones, which is how they got their name, and all are nocturnal. They are the only primates to eat only animal matter, feeding primarily on insects, but are also known to prey on birds and snakes. While their extinct relatives are found in Asia, Europe, and North America, tarsiers are now only found on several Southeast Asian islands including the Philippines, Sulawesi, Borneo, and Sumatra.

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