  We demonstrate theoretically that the characteristic feature of a 2D system
undergoing $N$ consequent Lifshitz topological transitions is the occurrence of
spikes of entropy per particle $s$ of a magnitude $\pm \ln 2/(J-1/2)$ with $2
\leq J \leq N$ at low temperatures. We derive a general expression for $s$ as a
function of chemical potential, temperature and gap magnitude for the gapped
Dirac materials. Inside the smallest gap, the dependence of $s$ on the chemical
potential exhibits a dip-and-peak structure in the temperature vicinity of the
Dirac point. The spikes of the entropy per particles can be considered as a
signature of the Dirac materials. These distinctive characteristics of gapped
Dirac materials can be detected in transport experiments where the temperature
is modulated in gated structures.
