part_of part of part of only in taxon Eumetazoa ectoderm stomodeum http://upload.wikimedia.org/wikipedia/commons/9/93/Gray977.png consider indicating location. e.g. anterior. Note some AOs place this as part of oral opening, but it's not clear when this structure comes into existence stomodeal This class groups together disparate structures as all being the anterior part of the early metazoan digestive tract and precursor of the mouth. However, the developmental processes vary, so this class may be split in future. E.g. in mammals it is a rostral depression surrounded by prominences. Outgrowth of the prominences produces a stomodeal cavity. subdivision of tube future mouth