In September of last year, I featured a couple examples of Nicolás Gajardo Henríquez's dinosaur origami. Flickr user origamiPete also has a fondness for things paleo. Here are some of his.
The Mesozoic aquatic bird Hesperornis:
Pete has also done some other ancient creatures, including the hammerheaded amphibian Diplocaulus and the saber-toothed cat, Smilodon.