Ancient skull fills big fossil gap.

A skull recently unearthed in eastern Africa and belonging to the same evolutionary lineage as modern humans ranks as a "one from a million" addition to the hominid fossil record.

The approximately 1-million-year-old specimen-consisting of much of the braincase and parts of the face and jaws--represents the only substantial Homo cranium from between 1.4 million and 600,000 years ago.

At least one feature of the cranium looks like later H. sapiens, although in several other ways the specimen veers toward H. erectus, concludes a team led by geologist Ernesto Abbate of the University of Florence in Italy. If correct, their analysis indicates that skeletal traits typical of H. sapiens began to emerge about 300,000 years earlier than many scientists had thought.

"The main point is that we have a well-founded date of about I million years for this Homo skull," Abbate says. "it fills a big hole in the fossil record."

Cleaning and restoration of the skull are still under way The researchers have refrained from assigning it to a species until they can compare it in detail to other ancient Homo craniums.

Excavation of the skull occurred between 1995 and 1997 at a site bordering a geologic formation in Eritrea known as the Danakil Depression. The site, situated about 30 miles southwest of the Red Sea near the village of Bula, also yielded a pair of teeth and two pelvic fragments assigned to Homo.

Bones from a variety of animals turned up in Homo-bearing sediment, the researchers say. These included gazellelike creatures and extinct forms of horses, rhinoceroses, and hyenas.

Several features of the Eritrean Homo cranium appear in African specimens assigned to H. erectus or H. ergaster, Abbate and his coworkers report in the June 4 Nature. For example, the new find has a long, oval-shaped braincase with a considerably smaller volume than that of H. sapiens. Also, a visorlike bony crest runs horizontally above the eyes.

However, the sharp angling and distinctive shape of the cranium near its midpoint strongly resemble early H. sapiens specimens, the investigators assert.

The Danakil cranium is missing its base, a repository of clues regarding the hominid's vocal tract structure and speech capacities.

Changes in Earth's magnetic field documented in Danakil's sediment layers, combined with previously known time ranges for extinct creatures found at the site, place the Homo material at about I million years old.

"If the dating is accurate, this is a very important find for the hominid fossil record," comments anthropologist Ian Tattersall of the American Museum of Natural History in New York.

No scientific consensus exists on how to identify fossil members of H. sapiens, Tattersall adds. The Danakil skull displays few obvious anatomical links to H. sapiens and maintains a murky evolutionary status, he contends.

"This is a terrific find, and the dating looks good," remarks anthropologist Tim D. White of the University of California, Berkeley. "It establishes the Horn of Africa as a key area for unraveling Homo evolution."

White calls the evolutionary analysis of the Danakil cranium conducted by Abbate's group "very preliminary."

The new find should help to address controversies in Homo evolution, the Berkeley scientist notes, such as whether H. erectus was a direct ancestor of H. sapiens and whether a number of ancient Homo species existed simultaneously (SN: 5/31/97, p. 333).