This early group flourished from the Upper Triassic to the end of the Jurassic. When we first see them in the fossil record they have developed three families, so biologists know their early evolution is not yet revealed. These three families are represented by the three genera "Rhamphorhynchus", "Dimorphodon" and "Eudimorphodon". This sub-order was the earliest kind or pterosaur, which were succeeded by the more 'derived' short-tailed pterosaurs, the Pterodactyloids, such as "Pterodactylus". In the Upper Jurassic both the two sub-orders were extant (living).