"When you start to open all these boxes, often times you find all kinds interesting pieces of paleontology," he said.

"The collector alerted us that it was an important fossil," Toscano said, adding that the skull remains carefully packed in a box in the museum's paleontology collection.

Both Blanco and Toscano said they hoped the find would attract more resources to museums in the developing world such as Uruguay's — which is so strapped for cash it has been unable to hold public exhibitions since 2000.

Associated Press writers Raul Garces and Alfonso Castiglia contributed to the report from Montevideo, Uruguay.

On the Net:

Proceedings of the Royal Society B: publishing.royalsociety.org/index.cfm?page1087

Uruguay's National Museum of Natural History and Anthropology: http://www.mec.gub.uy/munhina/index.htm