Higher Primates May Have Asian Root.

Researchers working in southern Asia have discovered 40-million-year-old fossil teeth and jaw fragments that, in their view, support the controversial notion that anthropoids originated in Asia.

The find in Myanmar represents a new species, Bahinia pondaungensis, in the anthropoid group, which includes monkeys, apes, and humans, reports a team led by anthropologist Jean-Jacques Jaeger of Universite Montpellier-II in France. The teeth show key similarities to those of Eosimias, a 45-million-year-old fossil creature from China that may also have been an early anthropoid (SN: 11/11/95, p. 309).

"The Bahinia find tells us that there was a complex community of primates living in Asia, with a tremendous anthropoid radiation much earlier than [many scientists] thought," Jaeger holds.

As with the Chinese material, however, classifying Bahinia as an anthropoid proves controversial. Critics say that Jaeger's group lacks sufficient skeletal evidence to justify its conclusion.

In contrast to the recent Asian finds, excavations over the past 40 years in Africa--especially at a rich Egyptian site--have uncovered extensive evidence of anthropoids dating to 36 million years ago (SN: 7/1/95, p. 6). Africa, the birthplace of the human evolutionary family, has received much mention as the possible ancestral home of anthropoids.

Jaeger and his coworkers view their new find as evidence for a much earlier origin of anthropoids in Asia, perhaps 55 million to 60 million years ago. In November 1998, the researchers recovered two fragmentary upper jaws and a broken lower jaw, each retaining a number of teeth, belonging to Bahinia. The same excavation level yielded the lower jaw of a previously identified species known as Amphipithecus. Jaeger's group views Amphipithecus as a more anatomically advanced anthropoid that lived at the same time as Bahinia.

Bahinia's teeth exhibit a unique combination of anthropoid features along with traits of more primitive, tarsierlike primates from nearly 60 million years ago, the researchers report in the Oct. 15 SCIENCE. Compared with Amphipithecus, Bahinia resembles a "living fossil," they contend.

Bahinia's teeth look enough like those of Eosimias, to place both creatures in the same evolutionary family, which may have been a sister group of the family that includes Amphipithecus, Jaeger's group says.

Bahinia's dental anatomy adds further support to the view that Asian anthropoids developed from creatures related to modern tarsiers, the team adds.

"The Bahinia fossil is closely related to Eosimias," comments paleontologist K. Christopher Beard of the Carnegie Museum of Natural History in Pittsburgh. "This reinforces the view that anthropoids originated in Asia." Beard directs ongoing excavations of Eosimias remains in China.

Elwyn L. Simons, an anthropologist at Duke University in Durham, N.C., views such assertions as premature. "Neither the Bahinia nor the Eosimias finds are complete enough to show critical anatomical features of anthropoids," says Simons, who directs primate excavations at an Egyptian site. "The case for anthropoid origins in Asia is as shaky as ever."

For instance, because no skulls are available for the Asian creatures, it's impossible to know if they had a fused forehead bone and a closed bony plate in the eye sockets, features characteristic of all anthropoids, Simons holds. The same anatomical uncertainties apply to Amphipithecus, he adds.

Beard and his coworkers, however, have discovered fossil limb bones from Eosimias, including parts of the lower leg and ankle, that, they argue, exhibit features found only in anthropoids.

Even if further discoveries confirm the anthropoid status of the Asian creatures, Simons remarks, no fossil evidence indicates that anthropoids later spread through Asia and founded African populations.