The amazing thing about these rocks being from Cambrian period, is that animal life on earth was developing rapidly; it was called the "Cambrian Explosion". "The Cambrian lasted 53.4 million years from 538.8 million years ago to 485.4 mya. By the end of the Cambrian, nearly all the major groups of animals we know today (the phyla) had evolved."   Dinosaurs first appeared about 230 Mya - quite recently really.