However, not all mammals still have a deciduous dentition. For example, all rodents retain their deciduous incisors into adulthood, and many, including the extremely diverse muroid rodents (>1400 species), no longer have deciduous teeth. Marsupials generally never erupt their deciduous teeth. read more
Then, as the animal gets a full-sized jaw, it loses the baby teeth and the second set of teeth emerges for the adult diet. Some mammals have more than two sets and some have none. The baleen whale’s teeth never erupt above the jaw. read more
Deciduous teeth, commonly known as baby teeth and temporary teeth, are the first set of teeth in the growth development of humans and other diphyodont mammals. They develop during the embryonic stage of development and erupt—that is, they become visible in the mouth—during infancy. read more