Permanent streams do not exist in northern or central Chad.

The skull, between six and seven million years old, was found in the Djurab desert of northern Chad in 2002.

Since the cease-fire, there has been no major fighting in northern Chad, the scene last year of heavy Libyan losses.

As southerners they did not become involved in later insurgent movements that developed in central and northern Chad.

Its fossil was found in northern Chad.

The accord was not respected by Libya, which maintained at least 3,000 men stationed in northern Chad.

The Libyans have been driven from most of northern Chad.

Libya has bombed targets in northern Chad almost daily since early last month.

As part of the cease-fire, Libya has agreed to stop its air raids, which have punished towns in northern Chad over the past month.

In 1998, a new rebellion broke out in northern Chad, and continued to escalate throughout 2000.