 Darwin 's view – that gaps in the fossil record accounted for the apparently sudden appearance of diverse life forms – still had scientific support over a century later . 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 . 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 " . 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 . 
