Does dark matter consist of baryons of new stable family quarks?

We investigate the possibility that the dark matter consists of clusters of the heavy family quarks and leptons with zero Yukawa couplings to the lower families. Such a family is predicted by the approach unifying spins and charges as the fifth family. We make a rough estimation of properties of baryons of this new family members and study possible limitations on the family properties due to the direct experimental and the cosmological evidences, studying the cosmological evolution of the fifth family clusters.