An African collector of fossils for Kenya's national museums was walking in the Samburu Hills early one morning when he found a piece of jawbone that may be of ''central importance to the study of human origins.''
Kiptalam Chepboi took the fragment to the leader of a Japanese team of paleontologists, Dr. Hidemi Ishida, with whom he is working.
The fossil consists of a left upper jaw with five teeth in excellent condition. Its size indicates it belonged to an animal about the size of a female gorilla.
According to Kenya's foremost paleontologist, Richard Leakey, ''The fragment is more human-like than previously discovered hominoids from similar aged and older sites in Eurasia and Africa.
''The new fossil find may be as much as 8 million years old, and is now being scientifically dated.
''It is of central importance to the understanding of human origins because it belonged to an ancestral hominoid, one of the intermediate humanlike beings between the apelike Ramapithecus of 14 million years ago, and ourselves.''
''It is not like a chimp, a gorilla, or a human - in fact, it is like nothing else so far discovered.''
Dr. Ishida's team works in the Samburu Hills. Richard Leakey and his parents made most of their remarkable finds at Lake Turkana (Rudolph) in the Rift Valley of Kenya.