On D=11 supertwistors, superparticle quantization and a hidden SO(16)   symmetry of supergravity
  We consider a covariant quantization of the D=11 massless superparticle in the supertwistor framework. D=11 supertwistors are highly constrained, but the interpretation of their bosonic components as Lorentz harmonic variables and their momenta permits to develop a classical and quantum mechanics without much difficulties. A simple, heuristic `twistor' quantization of the superparticle leads to the linearized D=11 supergravity multiplet. In the process, we observe hints of a hidden SO(16) symmetry of D=11 supergravity. 
Igor A. Bandos, Jose A. de Azcarraga and Dmtri P. Sorokin