These are images culled from public domain sources. They have been cleaned up and presented at a higher resolution than one would generally be able to find online. If you are looking for images suitable for print format, this is a good deal. If you are only interested in digital format, you can get the images free elsewhere. But really at the price no point in going through the process of cleaning the files up yourself unless you enjoy that sort of thing.

Most of these images already are freely available on the Wikipedia commons, where they were shared with the intention of being freely used by other users. While the authors cite the illustrator, is she being compensated for her work? They're great illustrations -- you'll rarely find better. But I have penalize the company for selling what already is being given away for free.

Here's the wikipedia link: http://en.wikipedia.org/wiki/Category:Approved_dinosaur_images