Data for: Reproductive colonization of land by frogs: Embryos and larvae excrete urea to avoid ammonia toxicity

We conducted field work in Gamboa and at the Soberanía National Park, in Panama. We worked with foam nests and gelatinous clutches from four frog species species, during 2016–2019 breeding seasons. We collected data with permission from the Panamanian Ministry of the Environment (details provided in the manuscript). We conducted experiments in an open-air laboratory, at ambient temperature and humidity, at the Smithsonian Tropical Research Institute (STRI) in Gamboa. We performed laboratory analysis at STRI facilities in Gamboa and Panama City. We exposed egg clutches to ecologically relevant, species-specific control (well-hydrated) and dry conditions in the laboratory, based on their natural history. We quantified ammonia and urea concentration in developmental environments at multiple times to assess their accumulation over development and the effect of dry conditions on the amount of urea excretion at the latest sampling age. We quantified nitrogen excretion using a colorimetric approach with a commercial enzymatic kit (Boehringer Mannheim Cat. No. 10542946035). We also conducted standard 96-h LC50 tests for ammonia in all the study species to test ammonia tolerance during early development in terrestrial developmental environments. Aditional details are provided in the main manuscript and its repsective supporting information.