I have just come across the following, in Charles M. Joseph's Stravinsky and Balanchine.. It deals with Balanchine's choreography for new (1925) version of Stravinsky's Le Chant du Rossignol, which the young man made for Diaghilev's company:
Is this possible?

What does "never seen in any previous ballet" mean in this context? Joseph's ordinarily thorough footnotes are silent on the Danilova attribution. They do have a reference to Boris Kochno's and Alicia Markova's interviews in Francis Mason's I Remember Balanchine, a book I do not have. The reference come in a note to the next paragraph, and it's not clear to what it refers.

Ballet historians, please explain this extraordinary statement.

Of course, "Rossignol" passed from the active ballet repertoire even before I was born, but tours chaînés déboulés are old, old as the hills. There's even a chaîné papillon, allegedly dreamed up by Marie Taglioni for her student Emma Livry. It would have to be a distinctive use of the step which can be very tiny in terms of travel so you can use them as great little time-killers if you have a ballerina who can do lots of turns, which Markova could indeed do.

i suspect danilova is making reference to some particular 'twist' or position with/for chaine turns. or at least some 'odd' rate of performing them. she can't likely have meant that no one saw chaine turns as we know the classroom step today before ROSSIGNOL? can she? i think it's safe to assume that there's something missing here, to explain what precisely danilova was referring to.