  Fossil groups (FGs) are galaxy aggregates with an extended and luminous X-ray
halo, which are dominated by a very massive early-type galaxy and lack of L*
objects. FGs are indeed characterized by a large magnitude gap between their
central and surrounding galaxies. This is explained by either speculating that
FGs are failed groups that formed without bright satellite galaxies and did not
suffer any major merger, or by suggesting that FGs are very old systems that
had enough time to exhaust their bright satellite galaxies through multiple
major mergers. Since major mergers leave signatures in the stellar populations
of the resulting galaxy, we study the stellar population parameters of the
brightest central galaxies (BCGs) of FGs as a benchmark against which the
formation and evolution scenarios of FGs can be compared. We present long-slit
spectroscopic observations along different axes of NGC 6482 and NGC 7556, which
are the BCGs of two nearby FGs. The measurements include spatially resolved
stellar kinematics and radial profiles of line-strength indices, which we
converted into stellar population parameters using single stellar-population
models. NGC 6482 and NGC 7556 are very massive and large galaxies and host a
centrally concentrated stellar population, which is significantly younger and
more metal rich than the rest of the galaxy. The age gradients of both galaxies
are somewhat larger than those of the other FG BCGs studied so far, whereas
their metallicity gradients are similarly negative and shallow. They have
negligible gradients of alpha-element abundance ratio. The measured metallicity
gradients are less steep than those predicted for massive galaxies that formed
monolithically and evolved without experiencing any major merger. We conclude
that the observed FGs formed through major mergers rather than being failed
groups that lacked bright satellite galaxies from the beginning.
