Are Google, Yahoo the next dinosaurs?

— -- Charles Darwin famously declared that "natural selection" was Mother Nature's way of improving a species so it could advance.

Born in the early days of the Internet, Google, Yahoo and smaller competitors help billions of people navigate the Web each day. Now, they're scrambling to adapt their desktop services for the hard realities of the wireless world.

One of the biggest challenges: dealing with the matchbox-size screens of cellphones and other devices, which aren't hospitable to the ads that are the lifeblood of traditional search engines. Billions in potential ad revenue are at stake as social networks, location-based services and wireless search deliver instant answers to wireless users on the go.

"As hot as they are right now, Google and the others could become dinosaurs if they simply try to use their old business models," says Roger Entner, a senior vice president at IAG Research in Boston. But if they can adapt, he says, they could extend their dominance.

Even so, it's been tough slogging, says Phil Holden, director of online services for Microsoft.

"What we've learned is that loyalty on the PC doesn't necessarily transfer to the mobile phone," he says. The wireless world, he adds, "has a lot of different dynamics."

One thing everybody agrees on: The mobile Web is an advertising gold mine just waiting to happen.

The fledgling mobile search industry generated about $700 million in ad revenue in 2007, JupiterResearch estimates. By 2012, revenue is expected to hit $2.2 billion and keep rising. Jupiter analyst Julie Ask says mobile search could eventually eclipse the traditional Web, which currently generates about $20 billion in ad revenue.

No matter how things shake out, consumers will benefit, predicts Ford Cavallari of Monitor Group, a consulting firm in Boston that specializes in technology. Search rankings based on factors that have little relation to the quality of a product or service, such as the number of daily "hits" a website gets, or a paid advertisement placement, are about to become history, he says.