Pushing It!

It is of interest to note that tiny,fossil beasts in the sandstones of South Australia, dated at 555 million years, appear to be currently the oldest bilaterally symmetrical (with a distinct front and a back end) animals (https://www.theguardian.com/science/2020/mar/23/fossil-ikaria-wariootia-bilateral-organism-human-relative). The beast, about half the size of a grain of rice, has been named Ikaria wariootia, but, I think, that describing it as one of our oldest ancestors is pushing it a bit. Being bilaterally symmetrical is a feature that we (along with worms, arthropods, molluscs and vertebrates) share, but the feature is broadly a characteristic seen in animals that have directional movement. There is no reason why it could not be evolved on several occasions