Knight often restored extinct mammals, birds and marine reptiles in action poses, but his depictions of large dinosaurs as ponderous swamp-dwellers destined for extinction reflected more traditional concepts. In his catalogue to "Life through the Ages" (1946), he repeated views he had written earlier (Knight, 1935). He described the great beasts as "slow-moving dunces" that were "unadaptable and unprogressive" while conceding that small dinosaurs may have been more active. In fact, by their long survival in a world of many predators, herbivorous dinosaurs were as effective as they needed to be.