Already great answers here, but I'll go back even further. OP might be referring to when things started with bilateral symmetry as a body plan. Right about 600 million years ago right before the Cambrian period. Before that, most everything was radial symmetry. Think sea anemone. Once bilateral started you started getting two eyes and all sorts of fun stuff. We go back a loooong way !
What_species_is_that t1_jb8z6k9 wrote
Reply to When did this body type first show up? by Human1221
Already great answers here, but I'll go back even further. OP might be referring to when things started with bilateral symmetry as a body plan. Right about 600 million years ago right before the Cambrian period. Before that, most everything was radial symmetry. Think sea anemone. Once bilateral started you started getting two eyes and all sorts of fun stuff. We go back a loooong way !