Wrapped up an illustration project a little while ago that involved a femur of an extinct "false saber-tooth cat"--Nimravids were carnivores that co-evolved to have the big long fangs that one sees in a Smilodon, but that aren't quite related to modern kitties as we know them.
However, the niches are close enough that I was able to make use of a modern bobcat femur to inform my work...
I was adapting the line drawings that the scientist had made from the original fossil, and creating a shaded version that leaned on the bobcat bone for its structural integrity.
Tonight I'm going to see if I can whack out a stippled chalicothere molar. Ha! Stippling is a notoriously slow way of doing illustrations, since it literally goes One. Dot. At. A. Time. But the results can be nice when you put in the time, and it does have a "timeless" look that comes across nicely in publications. Wish me luck!