Lack of Transitional Fossils
     What lack?  In human origin, we have Australopithecus, Homo Habilis, Homo Erectus, Early Sapiens, Cro-Magnon, and modern humans.  There have even been finds that demonstrate transition between the species.  The 1972 find at the site of Koobi Fora in Kenya beautifully depicts a transition between Australopithecus and Homo Habilis.  We have  Ambulocetus Natans, a transitional form between land mammal and whale.  We have Archeopteryx, part bird, part reptile.
     With seismic upheavel, erosion, consumption by predatory or scavenging animals, and the possibility of punctuated equilibrium it is fortunate that we have the wealth of fossils we possess today.