Ptolemy’s parents descended from backgrounds that had strong endemic traditions in claiming their descent from Hercules (see Heracleidae).
In contrast, the traditional date for Troy’s fall, as derived from Eratosthenes, has only one witness, Thucydides, (1:12) to a critical link, which is the number of years from the fall of Troy to the return of the Heracleidae, a span of time that had many diverse figures given by other ancient authors.
His son by Hermione, Tisamenus, became ruler after him but was eventually killed by the Heracleidae.