In the early 1970s Wyatt Durham and Martin Glaessner both argued that the animal kingdom had a long Proterozoic history that was hidden by the lack of fossils.[76][77] However, Preston Cloud held a different view about the origins of complex life, writing in 1948 and 1968 that the evolution of animals in the Early Cambrian was "explosive".[78] This "explosive" view was supported by the hypothesis of punctuated equilibrium, which Eldredge and Gould developed in the early 1970s—which views evolution as long intervals of near-stasis "punctuated" by short periods of rapid change.[76]