We first note that
4x4−x2(4y4+4z4−1)−2xyz+y8+2y4z4+y2z2+z8=(4x4+y8+z8−4x2y4−4x2z4+2y4z4)+(x2−2xyz+y2z2)=(2x2−y4−z4)2+(x−yz)2.
The given equation is therefore equivalent to
(2x2−y4−z4)2+(x−yz)2=0.
It therefore follows that both x=yz and 2x2−y4−z4=0 must hold.
Substituting x=yz in the second of these equations, we obtain 2y2z2−y4−z4=0, which is equivalent to −(y2−z2)2=0. We see that z=±y must hold. For z=y=t, we obtain x=t2, and for −z=y=t, we obtain x=−t2. It therefore follows that the set of all solutions is
{(t2,t,t)∣t∈R}∪{(−t2,t,−t)∣t∈R}.