One other great source of 28mm dinosaurs is HLBS, who I don't think have been listed anywhere upthread.
They used to have a great range of a dozen or twenty types of dinosaurs, but for some reason they've retired most of the designs and just have five models on offer right now - they're
over here on HLBS's website.
It'd be nice if they brought back the whole range, but the stuff they do have at least includes their very nice velociraptors, a horde of evil little Compsognathus and some other nice smaller dinosaurs (hard to find in plastic or other forms) and a big T. Rex that looks good but I haven't seen in person. I do own all the rest of the dinos they currently offer, and they're all very nice.
My favourites have to be the velociraptors. They're straight out of the first
Jurassic Park movie, lots of character and animation in the sculpts!