 The results place turtles as a sister clade to the archosaurs, the group that includes crocodiles, dinosaurs, and birds.However, in their comparative analysis of the timing of organogenesis, Werneburg and Sánchez-Villagra (2009) found support for the hypothesis that turtles belong to a separate clade within Sauropsida, outside the saurian clade altogether.The origin of the reptiles lies about 310–320 million years ago, in the steaming swamps of the late Carboniferous period, when the first reptiles evolved from advanced reptiliomorphs.