The evidence against gradualism is extensive, but not readily admitted to in the popular press or textbooks. Although the fossil record for a given location on land may be discontinuous, the fossil record for organisms deposited in the ocean or large bodies of water is continuous. Studies by Stanley (3), Cheetham (4) and Stanley and Yang (5) examined all the available lineages of their respective groups (bryozoans and bivalves) through long intervals of time, using multivariate analysis of multiple character states. Both concluded that most of their species were static through millions of years, followed by the sudden appearance of new species. Williamson (6) examined the fossil record of mollusks in Lake Turkana, Kenya, and showed that there were multiple examples of rapid speciation and prolonged stasis, but no gradualism. Barnosky (7) examined a large number of different lineages of mammals, from mammoths to shrews and rodents that lived during the last two million years of the Ice Ages and found a few examples of gradualism, but many more which showed stasis and punctuation. Prothero examined all the mammals with a reasonably complete record from the Eocene-Oligocene (about 30-35 million years ago) beds of the Big Badlands of South Dakota and related areas in Wyoming and Nebraska (8). This study not only sampled every available lineage without bias, but also had much better time control from magnetic stratigraphy and wider geographic coverage than previous studies. With only one exception all of the Badlands mammals were static through millions of years, or speciated abruptly (if they changed at all). Stasis and sudden appearance of new species is the norm rather than the exception, as evidenced by the fossil record.
Evolutionists have used the excuse that the fossil record is not complete enough to be an accurate representation of the history of life on the Earth. A recent book, The Adequacy of the Fossil Record (9), examined the fossil record in terms of its completeness, bias (over and under representation of certain species and groups of organisms), and stratigraphic range (its completeness for a species over the entire history of its existence). Their conclusions were that the fossil record is surprisingly complete, with about 10% of all species that have ever lived being represented. There are some biases and stratigraphic incompleteness in the fossil record, but these problems can be estimated mathematically from the available data. There are many examples of stratigraphic gaps in the fossil record, with these gaps being the rule rather than the exception. In the past, it has been assumed that the gaps represent incompleteness of the fossil record. The authors suggest the "heretical" view that stratigraphic data should be used to test the phylogenetic relationships between species rather than assume that the relationships exist and that the fossil record is incomplete.
and no i didnt hear of that weak principle.