Valerius Maximus, Memorabilia IX 12, ext. 2:

Aeschyli vero poetae excessus quem ad modum non voluntarius sic propter novitatem casus referendus. in Sicilia moenibus urbis, in qua morabatur, egressus aprico in loco resedit. super quem aquila testudinem ferens elusa splendore capitis – erat enim capillis vacuum – perinde atque lapidi eam illisit, ut fractae carne vesceretur, eoque ictu origo et principium <per>fectioris tragoediae exstinctum est.

The poet Aeschylus’ departure was not voluntary, but the novelty of the occurrence makes it worth mention. He was in Sicily. Leaving the walls of the town where he was staying, he sat down in a sunny spot. An eagle carrying a tortoise was above him. Deceived by the gleam of his hairless skull, it dashed the tortoise against it, as though it were a stone, in order to feed on the flesh of the broken animal. By that blow the origin and beginning of more perfect tragedy was extinguished.

Vgl. (kürzer) Plinius, Naturgeschichte X 7 sowie Αἰσχύλου βίος 10, wo die Weissagung zitiert wird: „οὐράνιόν σε βέλος κατακτενεῖ - Vom Himmel her wird ein Geschoß dich töten.“