A group representing more than 2000 palaeontologists from more than 100 countries has written to the Victorian government over concerns that plans to extend a Beaumaris yacht club will damage an internationally significant fossil site.

In a letter to Environment Minister Lisa Neville, Society of Vertebrate Paleontology president John Long said the land and sea floor around the Beaumaris Motor Yacht Squadron was a crucial reference point for dating and understanding mammal evolution in Australia.

Tim Flannery is concerned a plan to extend Beaumaris yacht club would damage a nearby fossil site. Credit:Joe Armao

A palaeontologist at Flinders University in Adelaide, Professor Long said Beaumaris rated among the country's top 10 fossil sites. He said it was particularly significant given it captured marine and land life, with some fossils dating back 66 million years.

The Royal Society of Victoria and the US-based Paleontological Society have also expressed concern over the site's future. In recent days, each organisation has released a position statement outlining the scientific significance of the area and their objection to a proposal to expand the Beaumaris Motor Yacht Squadron between Ricketts Point and Mentone Beach.