Ian Thorne is a pseudonym of Julian "Judy" Chain May Dikty.
Julian Clare May is an American science fiction, fantasy, horror, science and children's writer who also uses several literary pseudonyms, best known for her Saga of Pliocene Exile (Saga of the Exiles in the United Kingdom) and Galactic Milieu Series books. - Wikipedia
Her husband was writer T. E. Dikty (1953–1991).