The palaeopsychrosphere in the Devonian

The interpretation of Palaeozoic marine benthonic ostracods of the Thuringian ‘Ecotype’ or ‘Mega-assemblage’ as indicative of a palaeopsychrosphere has been controversial. We review the evidence and conclude that the characteristics and distribution of these ostracods are consistent with the existence of deep, cold, well-oxygenated water masses, formed by high-latitude sinking of surface waters, in the Devonian oceans, comparable with those of...