Fossils show how the complexity of living organisms has changed over time. Gerobatrachus hottoni was a unique organism that lived during the Permian period between ancient salamanders and ancient frogs. Scientists have nicknamed this organism the “frogamander” because it is believed to be a common ancestor of both modern frogs and salamanders. A frogamander. Which type of fossil is Gerobatrachus hottoni most likely to be? intermediary phylogenic transitional index