Superheroine poses have gotten so ridiculous that even a trained contortionist can't imitate them. But if you need more evidence, just check out the awesome new Tumblr called Escher Girls. The motto: "Float like a Butterfly. Sting like a WTF?!". There's example after example of the completely insane, antomically incorrect poses women strike in comics — plus a great comic that rebuts the "false equivalence" argument that says men are depicted in equally ridiculous ways. [Escher Girls, thanks Spocko!]
I understand what the site is getting at, but I don't agree fully with all of it's examples. In some cases, the artist isn't even considering anatomy, but is more concerned with shape and composition, or creating a mood. I think there's a bit of a double standard at play when only certain artists are taken to task for their "bad" anatomy, while guys like Sienkiewicz, McKeever, Bisley, Simonson, and Baker are lauded for theirs. I also think it's absurd that people focus on the unrealistic quality of the figure work, while not batting an eye at the implausibility of most super powers, or the physics shattering bad science the average comic fosters on the reader. If you're not looking for reality in the premise, why are you so hung up on reality in the human form? It's just a cartoon. It doesn't have to look natural.