are sharks mammals?
They are ovoviviparous
Great white shark
 Great white sharks are ovoviviparous, which means eggs develop and hatch in the uterus and continue to develop until birth. 
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.
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Great white shark [SEP] Reproduction
Great white sharks are ovoviviparous, which means eggs develop and hatch in the uterus and continue to develop until birth. The great white has an 11-month gestation period. The shark pup's powerful jaws begin to develop in the first month. The unborn sharks participate in oophagy, in which they feed on ova produced by the mother. Delivery is in spring and summer. The largest number of pups recorded for this species is 14 pups from a single mother measuring that was killed incidentally off Taiwan in 2019. The Northern Pacific population of great whites is suspected to breed off the Sea of Cortez, as evidenced by local fisherman who have said to have caught them and evidenced by teeth found at dump sites for discarded parts from their catches.