Embryonic blastopore = first opening of gastrulation; in protostomes becomes mouth, in deuterostomes becomes anus; oldest synapomorphy of bilaterian phylogeny; Hyman 1940 invertebrate treatise.
Embryonic blastopore = first opening of gastrulation; in protostomes becomes mouth, in deuterostomes becomes anus; oldest synapomorphy of bilaterian phylogeny; Hyman 1940 invertebrate treatise.