While it may sound like a cool idea to bring animals like the Tasmanian tiger back from extinction, new research shows this would come at the cost of other already threatened species.
The research published in Nature Ecology and Evolution found reintroducing extinct species would cost New South Wales and New Zealand three to eight-times more respectively than conserving threatened species.
Professor Hugh Possingham, chief scientist with The Nature Conservancy, said the researchers have spent 10 years helping the NZ and NSW governments prioritise their conservation money.
Their new research, he said, shows that resurrecting extinct animals would not be worth the cost.
"In terms of extinction the question arises, should we be investing in that? And I think our study suggests if it's not going to generate additional funds - if it's funding that would have otherwise gone to threatened species - then extinction is pretty expensive," he said.
"You get much bigger bang for your buck just looking after the things you've got."
Professor Possingham, who is also professor of mathematics and ecology at the University of Queensland, said there were many problems with the idea of bringing back extinct creatures.
"Even if you could get over all the technical barriers and one could get a thylacine or a moa to appear ??? that's only part of the challenge and the cost," he said.
"If a thylacine is born, who's going to teach it to be a thylacine? And how does it learn? And how do you get enough of them to create a viable population?"
Then, if scientists were able to breed enough of the animals to create a population large enough to sustain them, and somehow teach them how to be wild animals again, Professor Possingham said they might still be in danger in their original habitats.
"The world has changed, and some of the factors that caused them to disappear - some of them we know but sometimes we don't always know them," he said.
The Moa was probably wiped out by people and hunted to extinction by people, and fire may have had an impact, but we don't know how important introduced animals were, they could have been eating their eggs.
"And thylacines might have been affected severely by disease brought in by domestic dogs, and those disease may still exist."
So instead of looking to reintroduce extinct animals, the professor said we should put more effort and funding into the conservation of endangered animals.
"Analysis suggests the funding for conservation is probably a tenth of what's needed," he said.
"Not that there's much funding, but when we were working with the previous federal environment minister we were suggesting if there was another $100 million available a year across Australia for threatened species recovery we could probably start to stabilise the extinction rates, and get them back to a normal level."
"If you got one 2 billion injection of funds you could more or less stop the continent's extinctions."