Mammals show viviparity. Kangaroo, hedgehog, dolphin and loris are mammals. These give birth to young ones. Viviparous Mammals: Kangaroo, Hedgehog, Dolphin, Loris, Lion, Bat, Whale, Hippopotamus, Shrew, Cat Birds: Ostrich, Penguin, Kiwi Related Theory Viviparous animals are present in all groups of vertebrates except birds. Fish, amphibians, reptiles, and mammals all have members that are viviparous even though none of the groups is exclusively viviparous. Caution Echidna and Platypus are two egg-laying mammals. Ovoviviparous animals are those wherein the embryos develop in the eggs and remain in the body of the mother until they are capable of hatching.