I agree with snowgirl, Val. As soon as I read your posting, I thought of visual-spatial learners. They definitely read whole-words, as opposed to sounding them out. My son, DS8.5 is a strange mix, in that he is highly visual-spatial, reads way, way about grade level, but spell words in his own unique phonetic way. He will often spell the same word different ways within one writing assignment. His teacher is completely mystified by this, so I bought her a copy of Visual-Spatial Learners by Alexandra Shires Golon. I only hope that she reads it. You might want to see if a library near you has a copy, if you haven't checked out this book. It may be useful.
And as for your description of your son at a young age.. You could have easily been describing my son as well. Right down to the "could say names like "parasauralophus" correctly". How very interesting.
