belong to one of a few major families: box orbits, short-axis tube orbits, and inner and outer long-axis tube orbits [@dez85]. @schw82 also constructed a model of the triaxial ellipsoid with figure rotation around the short axis by properly populating different orbit families. Classifying orbits in a non-static potential is more difficult.

We performed a simplified classification of particle orbits using the last 4Gyr of the simulations when the galaxies are already merged. We defined one orientation of the coordinate system ($x,y',z'$) which coincides with the actual principal axes of the galaxy only at one or few particular moments. For the rest of the time only the major axis is along the $x$ coordinate.

We adopted modified criteria of orbit classification from @schw93 as recently used by @gaj15. Particles that keep a constant sign of the $x$-component of the angular momentum, $L_x$, are marked as *long-axis tubes*. Since the direction of the short axis is not stable, short-axis tubes are not classified in our case.

We also find orbits with low average values of the $x$, $y'$, and $z'$-component of the angular momentum. Specifically, we require the sum of these average values, $L_{xy'z'}$, to be less than 0.1M$_{\sun}$kpc$^{2}$Myr$^{-1}$ (for comparison, 