So these are just a few WIP pictures I took as I was making the tail. I don't think I can write a proper pattern for it, so hopefully the pictures will give you an idea of the steps I took to construct it. I have a rough pattern of the beginning steps that hopefully, the pictures will help you to interpret.
Tail: (working in rows)
Yellow:
Picture #1:
1. Ch 10
2. Sc 7, hdc, dc, ch 2, turn
3. hdc, hdc, sc 7, ch 1, turn
4-5. Sc 9, ch 1, turn (2 times)
6. Dec, sc 7
7. Continue sc along 3 edges of rectangle