Embryonic development of the monitor lizard, Varanus indicus

Describing the stages of normal development of Varanus indicus, the present paper provides the first developmental data on Varanidae. The incubation period is relatively long (180 days at 28 degrees C) and without any diapause. The development is rather slow during the first 50 days, after which a considerable acceleration can be observed. The stage of accelerated growth terminates at app. 100 days when all essential specificities of adult organisation (prolonged narial region with vomeronasal organ, eyes, claws, large heart and robust body and limbs) are established. The remaining period of the embryonic development is characterized by continuation of the respective trends, i.e., enlarging body, prolongation of rostrum, enlarging teeth and claws, keratinisation of claws and scales etc. In short, the second half of the embryonic development of Varanus is devoted to refining the structures supporting its adaptations for active predation.