Look at the surface of an animal, you will see what the animal looks like. Look beneath the surface, you will see why it looks that way. I’ve done a few musculature studies of fossil animals over the years, and these have been useful as both self-teaching method (to learn anatomy and muscle tone and art style) and also a way to show the differences between animals. I’ve not done a large variety, though. I have archosaurs, but of them there are no birds (egregious!) and even then, it’s “archosaurs” only so far as theropods, an ornithischian, and a croc. I need to expand my repertoire. That said, here’s what I’ve done.
I’d definitely be doing things differently now, with better attention to the abdominal muscle complex and to the position, size, and definition of the tail muscles. These were all done under the general assumptions that the base of the tail would normally be narrow, but as many have shown at this point (see here and references inside) the tail would be thicker, wide at the base and probably wider than the hips to some degree. I even failed to do this for a croc, for which this basal thickness is directly observable! I’ve done better since. For example, the oviraptorosaur “Ingenia” yanshini (or Ajancingenia, but there is growing disfavor around using the name based around its coinage) as part of this montage.
I think we all need to rethink how our animals are muscled out. Doing so will allow us to better drop skin over the top, and then whatever lies above that. It’s hard, but once you come through the difficulty of learning the many muscles (as I am still doing) and their relationships with the underlying and overlying anatomy, it’ll serve everyone — you, your viewers, and future observers of your work when you are gone and can no longer explain your ideas at the time — that much better.
I will get into how to adapt the muscle layer into the living animal (the progression of Peeling Back the Layers, but in reverse) in a future post, where I hope to talk about shrink-wrapping, and when and when not to do it (and yes, there are times it’s okay).