The ancestors of the Megalodon (Carcharocles megalodon) can be traced back to the Eocene, an epoch that took place around 56 to 33.9 million years ago. The evolutionary tree of this prehistoric basking shark begins with the mako sharks, which developed in the Eocene.

The first direct ancestor of the Megalodon was Carcharocles Auriculatus , a small shark that also lived in the Eocene.From this point, the lineage continued to evolve until the Megalodon finally appeared in the early Miocene, around 23 million years ago.
Interestingly, the Megalodon did not belong to the same family as today's great white shark, as was long assumed. Recent research suggests that the Carcharocles Megalodon belonged to the genus Carcharocles and the family Otodontidae, while the great white shark is descended from a group of extinct mako sharks.

In this category you will find fossilised teeth of the ancestors of the  Carcharocles Megalodon. 

The currently known ancestors were: Carcharocles Auriculatus -> Carcharocles Angustidens -> Carcharocles Chubutensis - > Carcharocles Megalodon

Carcharocles AuriculatusCarcharocles auriculatus lived in the Middle to Late Eocene, i.e. 28 - 45 million years ago, and had a length of up to 9 metres. The teeth have large, serrated cusps that are coarsely toothed and a pronounced bulge on the lingual side of the root. The tooth of an adult C. Auriculatus is 8 - 10 cm long.

Carcharocles Angustidens Carcharocles Angustidens lived in the Early to Late Oligocene, i.e. 25 - 35 million years ago, and reached a maximum length of 11 metres. The teeth of C. AngustidensC. Angustidens is 9 - 10 cm long.

Carcharocles Chubutensis lived in the Early to Earliest Miocene, i.e. 15 - 23 million years ago, and reached a length of up to 12 metres It is the direct ancestor of the prehistoric giant C. Megalodon. The teeth show very reduced cusps with a clearly reduced notch and have a very fine serration.
The tooth crown is broad and the tooth root has only a small bulge on the lingual side. The tooth of an adult C. Chubutensis is 9 - 13 cm long.