In addition to sunlight, you need to use spotlights with a wide spread on the dinos to illuminate them... You use several spotlights that will allow us to see the dinos clearly and look natural at the same time... Lighting is a critical issue of 3D art and there's a couple of good lighting tutorials in the backroom.. but for the immediate, try using spots on the dinos with a wide spread and raise the strength of the lights until you can see things... And keep them far away enough so that they don't look like spotlights... :)