Both Bufo (an amphibian) and Calotes (a reptile) share certain common features. Both have a tympanum, which functions as the external ear, helping in sound reception. They also possess a three chambered heart, consisting of two atria and one ventricle, which is characteristic of amphibians and many reptiles. Additionally, both animals are oviparous, meaning they lay eggs for reproduction. However, they differ in other aspects such as skin type Bufo has moist, glandular skin without scales, while Calotes has dry, scaly skin. Fertilization in Bufo is external within direct development (tadpole stage), whereas Calotes shows internal fertilization and direct development. Hence, the shared characters between Bufo and Calotes are the presence of a tympanum, a three-chambered heart, and oviparous reproduction.