I started the skeleton illustration with tracing photos of the skeleton. The skeleton had a standing position as I needed for my concept. Even when drawing from the photo I always kept in mind that I was not just tracing the photo as is, but making sure that my lines depict the correct anatomical structure. This was especially important for the vertebrae and small bones in the flippers. I had to check my drawing over and over again and look at other sides of the skeleton and other photos of flippers and vertebrae from different angles to make it perfect. To put the skeleton in the correct position inside the body, I used the Puppet Warp Tool in Adobe Illustrator. After many tries, I could finally make some progress. I created groups of different parts of the skeleton (spine with the ribs, front and back limbs and a separate group for the flippers) and made adjustments one by one to have them as I wanted. Despite the instrument allowing you to change almost anything, it distorts a lot from the original drawing. And I had to adjust every line and every point to get the best result.