Lords of Creation in the Playground
Animals were created by the Shepherd, and come in many different forms.
The first animals were born out of the Font of Life, located somewhere in Demiurgia. This was during the early days of creation, when the world was covered in deep winter, so the only animals to survive were mammals such as wolves, bears, rabbits, deer, mammoth, and many more.
The Shepherd created the first birds from the bodies of mammals, and he gave them to the First Tree as a gift. Birds spread the seeds of trees, and in return, trees shelter the birds.
The Shepherd created reptiles and amphibians from the bodies of birds, and then created fish from the bodies of reptiles and amphibians. He created reptiles and amphibians largely on a whim, but created fish specifically for Mezzethera, as penance for creating a continent out of her oceans.