Life-forms appears explosively, or change suddenly in a way inconsistent with the observed usual varation in organisms.
But so what if life-forms appear explosively? Darwinian mechanisms are in fact very good at creating these appearances of design.
Richard Sternberg, Stephen Meyers, Paul Nelson, Jonathan Wells: “But there are solid empirical grounds for arguing that changes in DNA alone cannot produce new organs or body plans. A technique called "saturation mutagenesis"1,2 has been used to produce every possible developmental mutation in fruit flies (Drosophila melanogaster),3,4,5 roundworms (Caenorhabditis elegans),6,7 and zebrafish (Danio rerio),8,9,10 and the same technique is now being applied to mice (Mus musculus).11,12 None of the evidence from these and numerous other studies of developmental mutations supports the neo-Darwinian dogma that DNA mutations can lead to new organs or body plans--because none of the observed developmental mutations benefit the organism.” [Citations from original source]