The first mammal
The first mammal to be discovered was called, the Eozostrodon and it is the first mammal to ever exist. It is a mammal, but it lies eggs, much like the platypus. Scientists believe that it went extinct about 210 million years ago. They existed in the Mesozoic time and people debate if they were one of the first evolution of the therapists,{The first kind of reptiles}.
The first insect
The name of the first group of insects was called, TERRESTRIAL group. People believed that they existed about 410 million years ago. It lived during the Early Devonian Period before most big living organisms. The oldest insect fossil found was called, Rhyniognatha hirsti and is estimated to be 407 to 396 million years old.