I knew first hand, as a result of my own thesis research, that the oldest four-legged vertebrates, those from the Devonian Period, were more fish-like than any other known tetrapod. But were the most ancient tetrapods really more similar than more recent tetrapods to an entirely extinct group of Devonian fish (called elpistostegid fish) that evolutionists consider to be their ancestors? Or had I been duped by the power of suggestion?
I came to the conclusion that they really were more similar when I realized that if tetrapods had become extinct at the end of the Devonian Period, and if God had not introduced any others (except humans to ponder such things), then we would group Devonian tetrapods together with elpistostegid fish in a system of classification based on overall similarity.*
The same can be said for the earliest birds. If birds had become extinct at the end of the Jurassic Period, they would never have attained the anatomical diversity and thus the taxonomic stature that this amazing group of vertebrates presently commands. The oldest birds are nothing more than variations on the small carnivorous dinosaurian theme and should be grouped with these animals accordingly.
I did not intend to sound blasphemous, but I could not help but think that if all species had been created instantaneously, but at different times in Earth’s long geologic past, it would have appeared as though God lacked imagination, because the anatomies of “new” species could be observed to be simply modified versions of existing ones. At the very least, one would have to agree that when God started to create tetrapod species instantaneously in the Devonian, He created them with a remarkable number of elpistostegalian fish-like features. Later, as He continued to create different species of tetrapods throughout the Carboniferous Period, they increasingly lost their fish-like characteristics.
From my waning creationist perspective, I could not think of any reason why the oldest known tetrapods would have had to appear when they did in the fossil record, resembling in so many ways a contemporaneous group of fish. God could have introduced tetrapods at a time and with an anatomy so unlike any other living organism that no one would ever have dreamed of an evolutionary connection between these two groups.
Toothed birds and ancient fish-like tetrapods were not exceptions, but rather good examples of a pattern clearly displayed by the fossil record, once an individual was ready to accept that this record had been laid down over a very long period of time. These kinds of quandaries stayed with me and started pecking away at my conviction that there were no bridging anatomies between major groups of organisms and that all species that had ever lived had been created instantaneously by divine fiat.
I am always amazed how the full impact of some knowledge can be shrouded for years until one day, triggered by who knows what, wham! it hits ya right between the eyes. I had come to realize that different species of organisms characterized different sections of the stratigraphic column (illustrated in this post). But the pattern within the fossil record is even more telling, thought it took me very much longer to appreciate the significance of the fact that two anatomically similar species are much more likely to occur close together in time than they are to be far removed from each other in the geologic column. The non-random distribution of anatomically similar organisms in time was an observation so obvious I could but wonder why it had taken me so long to see it.
For example, we only find Greererpeton living on Earth during the Carboniferous Period. Animals anatomically very similar to Greererpeton, such as Colosteus and Pholidogaster (all three genera are grouped together in the Family Colosteidae), also occur close by in geological time. We do not find colosteids evenly spaced throughout the geologic column.
Anatomically similar species, much more often than not, appear in the fossil record at about the same time, or in rapid and sometimes overlapping succession. The rapid appearance and close clustering in time of similar organisms is referred to as adaptive radiation. The diversity of duck-billed dinosaurs, a good number of which I had seen in Alberta, is known only from the Cretaceous Period. There have been two species of elephants on the earth, and anatomically they are very similar. But they both live in modern times, one in Africa and the other in Asia. God could have created one of them to live during the Triassic period and saved one for today. But He did not. And fossil hominids—why are they only found in rocks deposited relatively recently? I could list hundreds of other groups of organisms that match this non-random distribution in geologic time.**
If, as the fossil record shows, anatomically similar species may overlap or closely succeed each other in time, then if God was creating every species individually, He preferred grouping similar species together in time. Obviously, God could have created anatomically similar species ex nihilo close together in time. But why do it with such consistency?
But perhaps what I was seeing in the fossil record, at least in the case of closely similar species, was not really “evolution,” but just variation within a created “kind.” If this was true, then maybe God had not created each species separately, but had rather seeded Earth with a smaller number of “kinds” at different times, from which all varieties later sprung.
Years earlier, when I attended the creationist conference in Montreal at which Dr. Gish spoke, it was suggested that the created kinds described in Genesis might not be synonymous with today’s definition of a species, and that our present notion of a species might thus be too restrictive. Perhaps a created kind could encompass all the species that we currently place within a genus, or even all the species and genera within a taxonomic family.
There was a certain appeal for me in the idea that some species could have evolved, because it reduced some of the strain between creationists and evolutionists by introducing natural mechanisms into the creative process. Furthermore, the notion that there were limits to “evolution,” that created “kind” boundaries could not be crossed (organisms could only reproduce “according to their kind”), was also comforting, because it demanded the existence of God to account for the origin of new “kinds” or organisms.
*I will often refer to anatomical similarities between organisms. Historically, overall anatomical similarity was used to classify organisms into the Linnaean hierarchical taxonomic system. However, classifying organisms this way does not necessarily match the hierarchical pattern seen if evolution occurred. Evolutionary biologists now group organisms together on the basis of shared derived characteristics. However, without first showing that there is good reason to look for evolutionary mechanisms to account for overall anatomical similarity, it would be pointless to speak of shared derived characteristics to a creationist, since they imply descent with modification. Creationists do however recognize overall similarity, so that is as far as I will get in this book.
**So-called “living fossils” do not invalidate this fundamental and overwhelming pattern of the fossil record. So-called “living fossils” are simply extant organisms, such as Limulus (the horseshoe crab) or Latimeria (the coelacanth), which are very conservative in their anatomy and have changed little over geologic time. Proof of this slow rate of change is found in the specimens that occur at different times in the fossil record. But these organisms first occur close together with anatomically similar species. (Incidentally, whereas other living fossils are known from fossils, neither Limulus nor Latimeria are known from the fossil record.)