Remember the Motorola RAZR? The famous clamshell, or flip phone, sold millions of handsets, convincing the world that the super-slim, super-light, and flippable form factor was the wave of the future.

But where are the clamshells now? In the latest research from Avian Research, none of the top 10 phones based on total monthly sales are flip models. Eight of the phones are candybar or "brick" designs, and two -- the LG Shine and LG Rumor -- are sliders.

Flip phones used to be preferred by many users because the screens wouldn't get scratched up in your pocket, it's harder to make accidental "pocket calls," and because, when opened, they're longer and can make it more natural to talk on. But now the design is considered dated, much in the way that the classic 1964 Western Electric Touch-Tone telephone is no longer in use: Though perfectly functional, it lacks modern styling and is now considered retro.

What happened? The mobile internet, that's what: Data services on cell phones means bigger screens, and those just aren't feasible on most clamshell devices. (Horizontal clamshells haven't fared too well, either due to their odd design.) If the iPhone has proven anything, it's that size -- once the most important selling point in the cell phone business -- has ceased to matter much. Consumers now want big screens, even if that means having to find bigger pants in which to store the phone.

RCR's Mike Dano reminds us of the most famous scene in 2001's Zoolander, in which Ben Stiller whips out a tiny cell phone and carefully opens it up, clamshell style. Imagine what Zoolander might instead be using today... a phone so large he'd need a burro to haul it for him. It's funny because it's true.