Dimensional dual hyperovals with doubly transitive automorphism groups

It is shown that if a d-dimensional dual hyperoval S over GF(q) has a doubly transitive automorphism group G, then either q=2 and G is of affine type, or q=4, d=2 and G@?M"2"2 or M"2"2.2. This improves the results in [C. Huybrechts, A. Pasini, Flag-transitive extensions of dual affine spaces, Contrib. Algebra Geom. 40 (1999) 503-532] in the following sense: q is shown to be even, and the shape of G is strongly restricted, including the case q=2.