FIG. 28.13 The earliest fossils of animals. (a) Among the oldest known macroscopic animal fossils is a frond-like form made up of tubular structures, preserved in 575-million-year-old rocks from Newfoundland. (b) The oldest known animal fossil showing bilateral symmetry is a mollusk-like form preserved in 560–555-million-year-old rocks from northern Russia. (c) The oldest tracks and trails of mobile animals are found in rocks 560 million years old and younger.