Well, i just wanted to say that the outline on the rhino looks a little to thick compared to the inside details. It looks out of place. It is really, REALLY detailed, but i think you should go for a more consistent line width, or two line widths that are very similiar.
Other than that minor quibble, your anatomy, composition, and lighting are excellent.
Darren - That Roadkill is beautiful! Nice work! I love your hatching technique on the shading. I probably asked you this before - so I apologize that I forgot, but are you inking digitally?