last common ancestor of bilaterian animals
... that the last common ancestor of bilaterian animals has been reconstructed as a tiny worm with a combined mouth and anus?
... that the <b id="mwGcs"><a href="./Urbilaterian" id="mwGcw" rel="mw:WikiLink" title="Urbilaterian">last common ancestor of bilaterian animals</a></b> has been reconstructed as a tiny worm with a combined mouth and anus?