Several extinct genera of sea turtles have been identified through fossil records. Some notable extinct genera include:

1. Archelon - Known for being one of the largest sea turtles ever discovered, Archelon lived during the Late Cretaceous period and is characterized by its massive size and distinctive shell structure.

2. Protostega - Another large sea turtle from the Late Cretaceous, Protostega had a more streamlined body and a reduced shell compared to modern sea turtles.

3. Toxochelys - This genus was prevalent during the Late Cretaceous and had features that were intermediate between modern sea turtles and their ancient ancestors.

4. Osteopygis - Known from the Cretaceous of North America, Osteopygis is notable for its unique skeletal features that differentiate it from other genera.

These genera provide valuable insights into the evolutionary history of sea turtles and their adaptations over millions of years.