what does this word mean?
Ovoviviparous animals have the embryos develop inside eggs that remain in the mother's body until they are ready to hatch.
Ovoviviparity
Ovoviviparity, ovovivipary, ovivipary, or aplacental viviparity is an outmoded term used as a "bridging" form of reproduction between egg-laying oviparous and live-bearing viviparous reproduction. Ovoviviparous animals have the embryos develop inside eggs that remain in the mother's body until they are ready to hatch. 
when did the great white shark first appear The earliest-known fossils of the great white shark are about 16 million years old, during the mid-Miocene epoch. are sharks mammals? They are ovoviviparous
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Ovoviviparity [SEP] Introduction
Ovoviviparity, ovovivipary, ovivipary, or aplacental viviparity is an outmoded term used as a "bridging" form of reproduction between egg-laying oviparous and live-bearing viviparous reproduction. Ovoviviparous animals have the embryos develop inside eggs that remain in the mother's body until they are ready to hatch. The young of some ovoviviparous amphibians, such as "Limnonectes larvaepartus", are born as larvae, and undergo further metamorphosis outside the body of the mother. Members of genera Nectophrynoides and Eleutherodactylus bear froglets, not only the hatching, but all the most conspicuous metamorphosis, being completed inside the body of the mother before birth. Among insects that depend on opportunistic exploitation of transient food sources, such as many Sarcophagidae and other carrion flies, and species such as many Calliphoridae, that rely on fresh dung, and parasitoids such as tachinid flies that depend on entering the host as soon as possible, the embryos commonly develop to the first larval instar inside the mother's reproductive tract, and they hatch just before being laid or almost immediately afterwards.