Wyoming fossils shake up views of early primate migration.

Teeth and jaw fragment belonging to what may be the oldest known ancestor of modern primates, which include monkeys, apes and humans, have been uncovered in northwestern Wyoming, according to paleontologist Philip Gingerich of the University of Michigan in Ann Arbor. The discovery, he says, suggests that early primates migrated from Africa to Asia, then on to North America and finally to Europe.

Prior to this find, scientists assumed that while early primates originated in Africa, they came to North America via Europe.

The 53-million-year-old fossils combine features of two major primate groups from the Eocene epoch, which lasted from about 53 million to 37 million years ago. One type had shorter, broader teeth similar to those of modern tarsiers; the other had longer, narrower teeth similar to those of modern lemurs. But the remains lean more toward the lemur pattern, reports Gingerich in the Jan. 23 NATURE. He says the specimen represents the earliest known species of Cantius, a line of squirrel-sized primates that are extinct.

More complete remains of a 50-million-year-old species of Cantius indicate the creature had developed a grasping toe and forward vision, characteristics that cannot be identified with dental remans (SN:6/5/82, p. 372).

Although the new find includes only teeth and pieces of jaw, the fossiles are older than European Cantius remains, says Gingerich. Other animals represented at the Wyoming site, such as the "dawn horse" Hyracotherium, are smaller and more primitive than the same animals associated with European Cantius specimens, he adds.

"Based on present evidence," explains Gingerich, "it seems that the oldest ancestors of modern primates that have been found in Europe reached that continent by dispersal through North America."

Remains of early "true" primates have not been uncovered in Africa, he notes, because much of that continent's fossil deposits from around 50 million years ago have eroded and washed away. But there are several sings that modern primates originated in Africa, says Gingerich, such as the presence of lemurs on Madagascar today and the discovery last year of the jaw of a 33-million-year-old ancestor of the modern Asian tarsier in Egypt.

Gingerich speculates that early primates migrated from Africa to Asia and across the Bering Strait to North America. They then may have traveled to Europe over a land bridge that spans what is now the north Atlantic Ocean.

The new North American primate was discovered last summer by one of Gingerich's graduate students, Victor Torres. Gingerich dubbed the species Cantius torresi in honor of his student.

Other fossils at the deposit show that C. torresi lived in a subtropical forest that also contained primitive horses, early carnivores and alligators.