  Massive spin s>=3/2 fields can become partially massless in cosmological
backgrounds. In the plane spanned by m^2 and \Lambda, there are lines where new
gauge invariances permit intermediate sets of higher helicities, rather than
the usual flat space extremes of all 2s+1 massive or just 2 massless
helicities. These gauge lines divide the (m^2,\Lambda) plane into unitarily
allowed or forbidden intermediate regions where all 2s+1 massive helicities
propagate but lower helicity states can have negative norms. We derive these
consequences for s=3/2,2 by studying both their canonical (anti)commutators and
the transmutation of massive constraints to partially massless Bianchi
identities. For s=2, a Hamiltonian analysis exhibits the absence of zero
helicity modes in the partially massless sector. For s=5/2,3 we derive Bianchi
identities and their accompanying gauge invariances for the various partially
massless theories with propagating helicities (+/-5/2,+/-3/2) and (+/-3,+/-2),
(+/-3,+/-2,+/-1), respectively. Of these, only the s=3 models are unitary. To
these ends, we also provide the half integer generalization of the integer spin
wave operators of Lichnerowicz. Partial masslessness applies to all higher
spins in (A)dS as seen by their degree of freedom counts. Finally a derivation
of massive d=4 constraints by dimensional reduction from their d=5 massless
Bianchi identity ancestors is given.
