I first met a kangaroo rat as an undergrad attempting to do some field research on wild mice in California. In one of our live traps (essentially, a box containing seed bait, a ball of cotton to provide warm bedding for a few hours, and spring-closed door) I caught a K-rat. These animals have huge heads, comprising about a third of the length of their body, and are surprisingly docile. This one calmly sat on my palm until it decided to bound off into the chapparal.
Almost a decade later, I'm drawing K-rat skulls for the San Diego Mammal Project guide book to SD county mammals as a freelance scientific illustrator. It's been a years long project, and the end is near. I have drawn about 70 mammal skulls, with about 10 to go. Now I look back at the stippled drawings I did 3 years ago, and want to redo them because I've refined my technique, and those initial ones look amateurish. But if I started that, I'd be drawing skulls for ever.
Why skulls? Mammals are hard to spot; hence the lack of mammal watchers like there are bird watchers. They're shy and many are nocturnal. What we see are bits and pieces of evidence of their existence - footprints, poop, and skeletons.