This one was probably done in 2003. Part of the fun of world building is creating the details of a planet, a species, a culture. What do they eat? What do they wear? What kind of manners and religions do they have. What are the differences between the various cultures. Of the species in the Sentient 39 universe the Burrabb are the ones I’ve spent the most time thinking about and there’s still so much room in the picture for me to find color and nuance.
This sketch is the result of considering what sort of beasts of burden the Burrabb might have. A civilization is likely to need domestic animals in order to become a civilization. Species probably don’t go from hunter gatherers to space farers without a lot of steps in between.