 Owen, at the time a firm creationist, opposed the early versions of evolutionary science ("transmutationism") then being debated and used what he would soon coin as dinosaurs as a weapon in this conflict.With the paper describing Dinosauria, he scaled down dinosaurs from lengths of over 61 metres (200 ft), determined that they were not simply giant lizards, and put forward that they were advanced and mammal-like, characteristics given to them by God; according to the understanding of the time, they could not have been "transmuted" from reptiles to mammal-like creatures.In 1849, a few years before his death in 1852, Mantell realised that the genus today known as "Mantellodon" was not a heavy, pachyderm-like animal, as Owen was putting forward, but had slender forelimbs; however, his passing left him unable to participate in the creation of the Crystal Palace dinosaur sculptures, and so Owen's vision of the dinosaurs became that seen by the public for decades.