So I decided to take a trip down memory lane by re-watching the TV adaptation of "Dinotopia." Felt inspired by that, and some crazy dreams lately, to draw something like it. I know Dinotopia doesn't have carnivores to ride on, but I don't care. If I want a pet dinosaur, its gonna be a raptor!
I also experimented with perspective and angles. That took probably the most time. Hard stuff.
Actually it seemed as though most of dromeosaurs were in society, not the Rainy Basin (which seemed to have only the large carnivores). Therefor if one of them wanted to let their human companion ride, it would be possible.
Meanwhile - I'm super-de-duper impressed by the new ideas you experimented with in perspective and composition - it's very visually interesting. The Dino and the girl are both immaculate. The only thing I would change would be the castle/bridge in the background. It looks strangely flat and unmade next to your awesome dino wrangler. You could think about using a similar outlining style as the one on the foreground, but in a much, much more neutral, light tone(think goldy-grey). That way, the focal points in the fore(dino awesomeness), med.(bushes/waterfall), and background(castle/bridge) are all unified in style.