The female tyrant in the foreground is based almost entirely off the "sitting t-rex" mount showcased during the 2011 Dinosaur Expo at the Natural Science Museum in Tokyo and was referenced from photographs on Wikipedia. Triceratops was actually recycled from a 2008 pen and pencil drawing, which I updated with a thicker tail and quills.
If you are interested in purchasing prints or other gifts with this design, please visit my DeviantArt and CafePress pages.
Hat tip to Jack Horner - "scavenger-style" tyrants seem to get no love from the paleo-art community, and while I don't agree that rexes were obligate scavengers, I doubt they would turn their nose up at a free meal.
UPDATE: I can't leave well enough alone - I fixed some things that were bugging me about the foreground, added some detail to the moon, and some moonlit details on the 'trike.
2. Xu, X.; Wang, K.; Zhang, K.; Ma, Q.; Xing, L.; Sullivan, C.; Hu, D.; Cheng, S. et al. (2012). "A gigantic feathered dinosaur from the Lower Cretaceous of China." Nature 484: 92–95.
3. Horner, John R. and Lessem, Don. Simon & Schuster (1993). The Complete T. rex – How Stunning New Discoveries Are Changing Our Understanding of the World’s Most Famous Dinosaur.