Complex sentence: As a dancer, Fonteyn made her last appearance in Nureyev's 1979 summer season, and in February 1986 (aged 66) she appeared on stage for the last time, as the Queen in "The Sleeping Beauty".
Split into simpler sentences: As a dancer, Fonteyn made one of her last appearances in Nureyev's 1979 summer season. In February 1986 (aged 66) she appeared on stage for one of the last times, as the Queen in "The Sleeping Beauty".