Tambach-Dietharz, Germany - A fossil of a four-legged cat- sized reptile that was found in Germany may be a missing link in the evolution of mammals, palaeontologists said Monday.

The Bromacker stone formation at Tambach-Dietharz in central Germany is one of the world's richest spots for fossils, giving clues to life 300 million years ago before either mammals or dinosaurs walked the earth.

Excavation director Thomas Martens said only the 6-centimetre-long skull of the creature was found, but it was thought to have been a reptile 50 to 70 centimetres long.

"It could be a key stage in the development from reptiles to mammals," he said.

Scientists have been excavating land vertebrates from the Bromacker for 30 years and have found 40 individuals of 13 species. Martens said the fossils were better preserved than at sites of comparable age in North America and Mexico.

"The amazing similarities between the sites show they were all located on the continent of Pangaea," he added. But the site in Germany was 10 million years older and its animals much smaller than those in the Rocky Mountains.

This summer's dig was a joint effort by US, German and Slovak palaeontologists. The newest fossils are to be cleaned in Pittsburgh. Other finds included a cockroach wing and and a reptile the size of a mouse. (dpa)