The naturalist and wildlife broadcaster Sir David Attenborough has described a collection of Australian fossils neglected by the state's natural history museum as ''world class''.

On a break from his two-week speaking tour around the country, Sir David was taken to a site in NSW's central west where hundreds of ancient fish perished at the bottom of a small lake 360 million years ago.

Arguably one of the country's most impressive fossil deposits, the site reflects a time when fish ruled the world and animals were on the verge of walking on land.

Today, evidence of this event can be seen on several large rock slabs on display at Canowindra's Age of Fishes Museum.