Mantle plume hypotheses may rely on identifying mafic and ultramafic intrusions and coeval basalt volcanism. This volcanism was probably coeval with the emplacement of the Grenville dike swarm. The Late Tithonian is coeval with the Portlandian stage of British stratigraphy. The geologic sequences of the coeval Supai and Hermosa Groups. The Maastrichtian is roughly coeval with the Lancian North American Land Mammal Age. The Induan is roughly coeval with the regional Feixianguanian stage of China. It is coeval with the old European regional Saxonian stage. The Olenekian is roughly coeval with the regional Yongningzhenian stage used in China. The Pliensbachian is roughly coeval with the Charmouthian regional stage of North America. Taxation and representation are coeval with and essential to the constitution. The Ladinian is coeval with the Falangian Chinese regional stage. Coeval absolute sea-level rise and tectonic subsidence have strongly influenced delta evolution. According to Bertolini the town's foundation could be coeval to the Concordia Sagittaria's one.