Before mammals, before dinosaurs, before bacteria, or plants, there was something else; a protocell containing RNA.
The Exploring Origins Project has excellent animations of protocells, a timeline of life’s evolution, and best of all- fantastic animations of the RNA world.
You can see how RNA folds, ribozymes (RNA that catalyzes chemical reactions), and learn about the role of RNA when the Earth was young.
BTW- I made this ribozyme image with Cn3D. The RNA is synthetic – made by humans with machines, that is, and this molecule can cut chemical bonds.