Evolution by mistrali

Evolution

Yet from Morgoth's breeding of such hideous creatures, with tongues of flame and scales a sword might not pierce, came something fairer. For having created the Uruloki he found they had hearts and wills and thoughts of their own, and would not cleave to him as machines.

Some remained with him and became fearsome indeed; but many left Utumno and made their homes in dense forests, or burrowed into desert sands, or lurked in swamps and lakes. Yet others over the course of time grew wings and took to the air, and these became the birds so beloved of Manwë.