The vertebrate sequence is the subject Johnson deals with in chapter 6 of his book. Regarding the vertebrate sequence, evolutionists make the following general claims: amphibians developed from a common fish-like ancestor; reptiles developed from an amphibian ancestor; birds and mammals developed from a reptile ancestor. Included in the last claim is the assertion that humans and apes share a common simian ancestor. To support the first claim, that amphibians and fish descended from a common ancestor, some evolutionists point to the rhipidistians, a form of fish that Darwinists claim have certain important features bearing similarities to early amphibians. This claim, however, was refuted by Barbara J. Stahl when she asserted that those species thought to be the common ancestor of amphibians lived after the first amphibians appeared and therefore cannot be an ancestor of amphibians. Secondly, Stahl claims that the species that existed before amphibians do not demonstrate any characteristics likened to the first four-limbed creatures that walked on land. Thus, this first claim of the evolutionists has no conclusive evidence. The second claim, that reptiles descended from amphibians, also has no candidates to serve as evidence. One significant difficulty faced by evolutionists is the fact that the reproductive systems of the two classes are very different. In order to prove that the transition occurred, soft tissue from supposed ancestral links would need to be examined to show divergence in the direction of the differentiation we see in the two classes.
Lastly, Darwinists claim that mammals descended from reptiles. As a reminder, this is one of the conclusive proofs Stephen Jay Gould offered as proof of micromutational speciation. As evidence to support the claim, scientists point to the class of species known as Therapsida. The fossils placed in this category bear resemblance to both reptiles and mammals and thus, for evolutionists, provide the necessary link between the two. However, due to important structural differences in the fossils in the group, taxonomists have failed to successfully identify a single species that might serve as the single ancestral point from which all mammals descended – a crucial argument for Darwinists since mammals are strongly considered to be a “monophyletic” group. Some paleontologists developed a theory that mammals might be a polyphyletic group, that is that several mammalian groups developed separately from different lines of the therapsid category. It is important to point out here that if mammals are a monophyletic group with its own difficulties brought by the lack of evidence in the fossil record, then the problem is made exponentially worse if mammals are considered to be a polyphyletic group.
Within this last claim is the popular argument that reptiles were the predecessors to birds. Archaeopteryx, the reptile-like bird (or bird-like reptile), is cited as clear evidence of a transitional link. However, while some might concede that this could be some measure of proof, it too is not conclusive. One exception to the consistent pattern of the fossil record depicting sudden appearance of life is not enough to prove the opposite. Archaeopteryx indeed might be one distinct species among many distinct species that simply share certain characteristics. This does not immediately point to speciation through accumulation of micromutations, adaptation, microevolution, or even macroevolution. The fossil record and present-day life consists of specimens containing bewildering examples of both diversity and commonality and that simply points to the difficulties inherent in the process of classification.
The fact is that evolutionists approach the study of origins with preconceived assumptions and examine the apparent evidence in that light. For them, evolution occurred. Ancestors to present day organisms are often simply labeled as such because the evolutionists “know” they are there. However, this is far from a confirmation of the theory. Evidence must be evaluated independent of the assumptions made in the theory being tested. This is a basic premise of science that evolutionists dismiss in their work repeatedly.
Johnson turns to the so-called molecular evidence for evolution in chapter 7 of Darwin on Trial.
