Novel signatures of heavy quarks at the CERNSp¯pSand Fermilab Tevatron colliders

New heavy quarks with $m_Q<M_Z$, if they exist, are produced rather copiously at existing hadronic colliders. If they predominantly decay via unusual modes, thus giving rise to novel signatures, they could have so far evaded detection. The fourth-generation $b^{\prime }$ quark, with its diverse decay modes, is studied as an illustration. We focus on the signatures $ee+2j,p_T+2j$, and $\gamma +3j$, while more intriguing signatures are also discussed. Exotic quarks, such as vectorlike quarks, possess signatures that form a subset of these. However, the possible existence of the $\gamma +\mathrm{jets}$ mode is unique to $b^{\prime }$. Such quarks, if they exist in the appropriate mass range, could constitute a source of large background to the signals for supersymmetric particles, the Higgs boson, techniparticles, etc. We find that existing hadronic colliders should be able to discover these new heavy quarks if they fall inside the $\frac{M_Z}{2}\lesssim m_Q\lesssim M_Z$ range, and $m_Q<M_{H^0}$.