Because the first living things on Earth single-celled organisms, the earliest animal adaptation of all was the emergence of animal life itself. These single-celled organisms eventually gave rise to the six taxonomic kingdoms of fungi, eubacteria, archaebacteria, protists, plants and animals.
So far, the oldest known animals on Earth were ancestors of the comb jelly. This discovery was made by the National Science Foundation, using high-tech analysis of genetic data. Other early animal adaptations must have included consumption (feeding on other organisms), the ability to move and multicellular living (probably first in colonies, which led to the evolution of multicelled organisms).