A two-dimensional global hybrid simulation is carried out to study the ion velocity distributions in the dayside magnetosheath in the presence of a northward interplanetary magnetic field. In the simulation, the bow shock and the magnetosheath form self-consistently by the interaction between the solar wind and the geomagnetic field. Downstream of the quasi-perpendicular shock, the initial isotropic distribution of upstream ions first becomes an oval-shaped bi-Maxwellian distribution with the perpendicular temperature T⊥ greater than the parallel temperature T∥. These downstream ions are then found to evolve to a conic-like or D-shaped distribution in the high-latitude magnetosheath prior to the transmission into the magnetosphere. The presence of the D-shaped distribution is due to the adiabatic ion motion from the subsolar magnetosheath with a high magnetic field strength to high latitudes with a lower field, but not due to magnetic reconnection at the high-latitude magnetopause.