Scientists in Spain say that they have found a tooth from a distant human ancestor that is more than one million years old.
The species from which it came is not certain. (Scale bar: 10mm)
The tooth, a pre-molar, was discovered on Wednesday at the Atapuerca site in northern Spain's Burgos Province.
It represented western Europe's "oldest human fossil remain", a statement from the Atapuerca Foundation said.
The foundation said it was awaiting final results before publishing its findings in a scientific journal.
Several caves containing evidence of prehistoric human occupation have been found in Atapuerca.
In 1994 fossilised remains called Homo antecessor (Pioneer Man) - believed to date back 800,000 years - were unearthed there.
Scientists had previously thought that Homo heidelbergensis, dating back 600,000 years, were Europe's oldest inhabitants.
Jose Maria Bermudez de Castro, co-director of research at the site, said that the newly discovered tooth could be as much as 1.2 million years old.
"Now we finally have the anatomical evidence of the hominids that fabricated tools more than one million years ago," the statement said.
It was not yet possible to confirm to which species the tooth belonged, it said, but initial analyses "allow us to suppose it is an ancestor of Homo antecessor".
Mr Bermudez de Castro said the tooth appeared to come from an individual aged between 20 and 25.
"There is no doubt, from the (geological) level where the tooth was found, that it belonged to the oldest European found to date," the French news agency AFP quoted him as saying.
Fossil finds in Georgia in the Caucasus represent the oldest evidence of humans anywhere in Europe. Digging at the medieval town of Dmanisi, 80km (50 miles) south-west of Tbilisi, has yielded skulls that are 1.8 million years old.