Pharyngula

At the pharyngula stage, all vertebrate embryos show remarkable similarities, i.e., it is a "phylotypic stage" of the sub-phylum, ==The hourglass model==

The observation of the conservation of animal morphology during the embryonic phylotypic period, where there is maximal similarity between the species within each animal phylum, has led to the proposition that embryogenesis diverges more extensively in the early and late stages than the middle stage, and is known as the hourglass model. Comparative genomic studies suggest that the phylotypic stage is the maximally conserved stage during embryogenesis. ==See also==