An ambitious project to showcase the prehistory of the south coast of England, famous for its marine fossils from ammonites to giant sea reptiles, has attracted support from David Attenborough and Eden Project founder Tim Smit.

A former quarry on the Isle of Portland, Dorset, is being investigated as the site for the £85m Jurassica park for which the designer of the Shard building in London, Renzo Piano, has provided preliminary sketches of a domed glass and steel roof, according to the journalist behind the idea.

The site is within the 95-mile long Jurassic coast,a world heritage site because of its importance in understanding geological periods from 250m to 65m years ago.

Michael Hanlon, a science journalist, has made presentations to scientific leaders and businesses in a bid to raise interest and money for the project. For Hanlon, who was born and grew up in Dorset, "the heritage is really of the extraordinary marine fauna. It is the place where you can say science really began, where we suddenly realised we were living on a really old planet that used to be very different from what it is now."

David Attenborough: 'The area is one about which Britain can be very proud because it is the birthplace of paleontology.' Photograph: David Parry/PA

Attenborough, who, according to Hanlon, is patron of the project, said: "I do think fossils are very interesting and I think the area is one about which Britain can be very proud because it is the birthplace of paleontology." He admitted he did not know "what patron really means", but said the project was "a nice idea".

The idea of the theme park had grown thanks to the support of "chance encounters" with leading scientists and business leaders, said Hanlon. Smit, who was a trustee of the project, had "sort of not let me not do it".

There had been talks about a possible partnership agreement with the Natural History Museum involving loans of Jurassic-related objects, said Hanlon, who had also discussed the idea with the Royal Society and with Kokoro, the Japanese technology company that provided the animatronics for the museum's dinosaur gallery.

"We want to copper-bottom this. It is not a Legoland for dinosaurs", said Hanlon.

He believed the project, in a part of Britain where there have also been discoveries of flying reptiles and the occasional dinosaur, should be ready by 2020, attracting about 700,000 visitors a year. The price of admission for two children and two adults would be £50 to £70 at today's prices.

"If we can't raise the money, that is because there is something wrong with the idea", said Hanlon. "Everybody thinks of Dorset as rather a wealthy place. Actually it is not. The unemployment rate in south Dorset is appalling. . … Something like this would transform it in the way Eden has transformed south Cornwall."

Michael Dixon, dthe irector of the Natural History Museum in London, visited the proposed site in July. A spokeswoman for the museum confirmed there had been discussions about the project and though it would be happy to advise the project's creators, "we have not got any further at the moment".

One possible problem recognised by the scheme's proponents is transport. huttle buses from a big car park built to handle crowds going to Weymouth for the Olympics sailing in 2012 is one idea being considered.