Embryos of all species are primarily separated along PC1, associated with age (changes in FNP width, FNP shape, nasal pit width, internasal distance, width of oral cavity, intermaxillary distance, forebrain width, eye size, and head length). Along PC2, there is a three-way divergence of the species (changes in shape and width of FNP, internasal distance, nasal pit angle, forebrain height, oral cavity width, maxillary process angle, depth of ridge between forebrain hemispheres, and length of head and eyes).