James Gurney is an American artist, illustrator and author. He is most well known for illustrating and writing the Dinotopia book series. In addition to his fictional work, he has written two art instructions books: Imaginative Realism (2009) and Color and Light: A Guide for the Realist Painter (2010). I cannot speak highly enough about these books. I personally own Imaginative Realism and plan on purchasing Color and Light in the near future. They are great resources for any artist.
Additionally, Gurney is a frequent blogger (http://www.gurneyjourney.blogspot.com/). His blog is an amazingly varied resource that covers things like color theory, plein-air painting, and illustration techniques/materials. At the time of writing his latest post is on being caught drawing someone in public. I have to stop before I get too gushy but I’ll end this post by saying that the Dinotopia books were a huge part of my childhood and it was an amazing experience to come back to them as an adult (and budding illustrator myself), and to then find out that the person who wrote and illustrated them is so open, cool, and interested in sharing his knowledge and passion with others.
Sources: his website, his blog, and the Dinotopia website.