Four Chinese paleontologists recently announced in Nature magazine that they had discovered a skull and the jawbones of the oldest, well-preserved primate fossil unearthed in Asia.

They are "the best evidence of the presence of early primates" on the continent, and that "raises the tantalizing possibility that remote human ancestors might have originated in Asia," the Chicago-based Field Museum announced in a news release.

Chinese media called the discovery a "unique gift" just before the Year of the Monkey, which will begin with the Chinese Lunar New Year on Thursday (January 22).

But for Ni Xijun and the research team from the Institute of Vertebrate Palaeontology and Palaeoanthropology (IVPP), affiliated with the Chinese Academy of Sciences, the discovery marked only a small, though significant, step in their tortuous academic journey.

Their research is now funded by the National Natural Science Foundation of China, and their work has been listed as one of the major basic research projects of the Ministry of Sciences and Technology and the Chinese Academy of Sciences.

They hope their work will help satisfy people's curiosity about the origin and evolution of our distant ancestors -- euprimates, or primates of modern aspect.

Better still, they hope to determine how these prehistoric cousins lived.

"We discussed some possibilities in our paper (published in Nature magazine), but there are still so many unknowns," Ni said in a telephone interview with China Daily.

Ni is currently conducting research in New York with the American Museum of Natural History.

Possibilities

The skull and jawbones are very small, roughly 2.5 centimetres in length. They were discovered in the upper section of the Lingcha Formation, in Central China's Hunan Province.

The team members have determined the bones are 55 million years old, as the fossils were from the geological stratum identified by geologists and determined by modern technologies -- such as palaeomagnetic and chemostratigraphical studies -- as belonging to the Eocene Epoch, which extended roughly from 55 million to 34 million years ago.

The skull indicates the animal had a big brain and round forehead. Its eye sockets, each with a bony ring, indicate the primate had binocular vision.

"It had a very small body, even smaller than the smallest primate today, the mouse lemur in Madagascar," Li Chuankui, one of the co-authors, told China Daily while showing the writer the small skull of a modern-day tarsier, which was a little less than 3 centimetres long.

"We estimate it weighed 28 grams (about 1 ounce)," added Li.

Among the finds, the lower jaw and the upper dentitions were nearly complete. After examining both the upper and lower tooth rows, the researchers were able to determine, at least initially, that it might have eaten small insects.

Most of the early euprimates are known only from isolated teeth or jaw fragments, found in North America and Europe.

The researchers discovered the teeth of Chinese specimens were "closely similar" to those of the earliest primates, with the Latin name Teilhardina belgica, found in Europe.

By comparing the jawbones and teeth with those found in Europe and North America, the researchers concluded the most recent discovery appears to be just as old as the oldest primates found so far, in North America and Europe.

Giving it the Latin name Teilhardina asiatica, the IVPP palaeontologists determined the fossil to be the oldest primate ever found in Asia.

Ancient animal world

The paper was the culmination of "a lot of work," that stretched over many years, Li said.

The skull and jawbones were wrapped inside a small lump of stone, no more than a few inches in diameter.

It was tucked between other stones on a hill in rural Hengyang, in Central China's Hunan Province.

For palaeontologists -- researchers who look for fossils and study extinct animals and plants -- the rolling small hills, in what they call the Hengyang basin of red earth, are a palaeontological haven.

The area was first discovered by Yang Zhongjian (Young Chung-Chien), one of the pioneering Chinese palaeontologists, as early as the 1930s.

In the basin of what he called the "red beds of Hunan," Yang discovered one lower tooth of a horse-like animal in 1937, and published his find on the journal "American Museum Novitates."

But casual passers-by and local farmers see only the farm fields and red hills.

However, trained eyes plus professional instincts have enabled researchers to pick and dig from the outcrop interesting finds that help them piece together the puzzles of the earth's past.

Since the founding of New China in 1949, Chinese palaeontologists have made numerous research surveys in the area and found fossil skulls, bones and teeth belonging to 20-plus animals that lived millions of years ago.

Among them were horses, rodents, lizards and alligators.

Hu Yaoming was the researcher who found the fossil.

Hu is currently working at the Division of Palaeontology of the American Museum of Natural History.

Li said it took Xie Shuhua, a chief technician at the institute, two years to prepare the fossil skull and its teeth from the small lump of stone.

The analytical work took nearly three more years.

Their analysis indicated the small ancient primate mainly moved about during the day. So, the species was diurnal.

"That's not at all what I expected," Richard F. Kay of Duke University Medical Center in Durham, North Caroline, was quoted by the American Association for the Advancement of Science as saying.

The finding suggests that the first primate ancestor may have been diurnal, too, according to Kay.

Robert Martin, from the Field Museum in Chicago, however, notes that the skull has a large opening on the snout for the nerve connected to the whiskers, which tended to be more developed in nocturnal mammals.

The Chinese researchers stressed their finding only pointed to one possibility and was not conclusive.

Ni said they had followed strict professional practices during their analytical work.

The researchers examined and compared the data of 303 dental, cranial, post cranial and soft tissue characters and 52 taxa, or classified groups of mammals.

"The work was arduous, as there were tons of data," Ni recalled. "We couldn't afford to miss any clue that revealed the evolution of the ancient primates from the existing fossils."

Thus, Chris Beard of the Carnegie Museum of Natural History in Pittsburgh, Pennsylvania, commented that the new discovery that the earliest modern primates had small eyes turns the traditional view of primate evolution "on its head," according to Nature magazine.

What lies ahead?

Whatever the argument, their findings have laid the foundation for further research into the "many unknowns."

For example, Li said it has been widely believed mammals couldn't travel between Asia and Europe around 55 million years ago.

The landmass of Eurasia was thought to be "largely or completely split down the middle by a combination of the Western Siberian Obik Sea to the north and the Turgai Straits to the south," Martin noted.

However, the Teilhardina asiatica found in China, which shares so many features with its cousins in Europe, suggests it was possible for mammals to trek across Eurasia in those days.

"Abundant fossils of earlier primates found in China indicate Asia was an important platform for the euprimates to appear and evolve," Ni wrote two years ago in the team's application for research funding to the National Natural Science Foundation of China.

The researchers' job now is to link the Chinese fossils together, and then to link them with their cousins found in other places in Asia as well as in Europe and North America.

(China Daily January 19, 2004)