Period versus age for early fast rotator pMS stars of NGC 2264. Their positions in the period-age plane are compared with models assuming evolution with constant angular momentum. Masses in the interval 0.2 <M/M_⊙< 0.3 correspond to °, 0.3 <M/M_⊙< 0.4 to ▪, 0.4 <M/M_⊙< 0.6 to △ and all the remaining to ×. Solid lines represent models with J_in = J_kaw , while the dashed lines stand for models with J_in = 3J_kaw.