No new phyla, classes, or orders have appeared (Talk.Origins)
No new phyla, orders, or classes have been observed appearing. Macroevolution remains unobserved.
Curiously no source is given for this claim. This actually seems to be a merger of two different claims.
(Talk.Origins quotes in blue)
1. Evolution works almost exclusively by gradual changes. It has taken hundreds of millions of years of evolutionary divergence to produce the existing phyla, and probably hundreds of thousands of years at least for classes to develop. For a new phylum, order, or class to arise suddenly would be creationism, not evolution.
So Talk Origins agrees that the first part of this is true.
2. Macroevolution is evolution at or above the species level, which has been observed.
As long as Macroevolution only refers to variation at or above the species level then this is true, since that level of variation is observed and is consistent with Created kinds. However such variation neither proves a universal common ancestor nor does it show an increase in complexity or information.
3. Evidence is not limited to seeing something happen before our eyes. Evidence for macroevolution includes the pattern of homology between organisms, the fossil sequence (including abundant transitional fossils), biogeography, and other evidence.
None of this constitutes scientific evidence for common descent, as all of it assumes the truth of evolution.
- Transitional forms
- (Talk.Origins) Homology can't be evidence of ancestry if it is defined thus
Furthermore, there are no plausible mechanisms that would prevent macroevolution, given the variation which we observe.
This is incorrect. Creationists do have mechanisms that limit variation: increased entropy, and increased genetic noise. Creationists have long held that, because of the laws of thermodynamics and the principles of information theory, the variations within Created kinds only go downward, not upward. That is, the increased variation results in a loss of information within each group, so that each new group is generally weaker and less fit than its ancestors.
Indeed, plausible mechanisms leading to diversity do exist.
Creationists have no problem with diversity. However, increased diversity does not prove a universal common ancestor.