In the original version of this picture I had the dinosaur looking extremely unhappy. In my mind it had some knowledge of the large scale extinctions to come. My youngest daughter suggested a happy dinosaur. So I tried that out (with eye brows) but figured the dinosaur needed something to be happy about. Not a momentary or superficial happiness; in the original version of the picture the dinosaur's sadness was deep and penetrating as it contemplated extinction. So I added the small mammals with the thought that the dinosaur was still thinking about extinction, but in a way that demonstrated a very long view of things, with sympathetic joy and equanimity.