Typical frog tadpoles filter feed and lack a digestively active stomach. Only during metamorphosis, do they develop a functional stomach allowing a shift to feeding on larger prey as an adult. The tadpole of Lepidobatrachus laevis, however, develops an adult-like stomach during embryogenesis and is capable of feeding on larger prey as a tadpole. Consequently, L. laevis does not undergo a significant dietary shift at metamorphosis. Earlier studies of L. laevis implicate the down regulation of retinoic acid (RA) as a possible mechanism in this novel adaptation. However, preliminary research only describes the gross morphology of tadpole stomachs treated with RA, begging the question what occurs at cellular and genetic levels during stomach development, and if it in fact recapitulates plesiomorphic stomach development. This study compares gut development of L. laevis treated with exogenous RA to that of Xenopus tropicalis (a model for typical frog development) treated with an RA inhibitor. The goals of this study are to assess if L. laevis stomachs treated with RA recapitulate the plesiomorphic stomach morphology and gene expression modeled by untreated X. tropicalis, and if X. tropicalis treated with an RA inhibitor show development of an adult-like stomach as in L. laevis stomachs, and gain insight for the roll of modified RA signaling in stomach evolution. Histological staining is performed to assess the effect of treatments at a cellular level. Transcriptome analysis is performed to assess the effect of treatments at a genetic level. This analysis will provide a greater understanding of the evolution of developmental modules, their role in the diversification of amphibian life histories, and how that diversification enables changes in diet and niche.