Just got it in the mail, and like it a lot. I saw it years ago at an airport, was reminded of it a few days ago, and decided to buy it online.
The Paleoartisans site from which I bought it isn't really well set up for taking online orders; but if you e-mail email@example.com your name, address, credit card information (card number, expiration date, and the three-digit security code from the back — the very things you'd routinely use to buy things online), authorization to charge you $18.75, T-shirt size, and color (select from these), you'll get the shirt in a few days. And, no, I'm not getting any money (or free shirts) from them.
The one thing I'd have liked even more would be a similar T-shirt with the text "People's Front for the Liberation of Gondwanaland." Also ordered recently, though from different sellers: A Curious George shirt, matching father-and-sons Russian Winnie-the-Pooh (Vinni-Pukh) T-shirts (CafePress), a Cheburashka and Crocodile Gena T-shirt (also CafePress), and a Che Burashka T-shirt (also CafePress):