As I continued my work in paleontology, other observations I was making on the nature of the fossil record began to gnaw away at the foundation of creationist belief that had been laid in my youth. Although my doctoral research focused almost exclusively on the skeletal anatomy of Greererpeton, an interesting pattern began to emerge as I compared it with similar tetrapods.
At localities elsewhere in the world where Greererpeton-like animals were known, the fossil fauna included a suite of extinct animals similar to those that had been found with Greererpeton near Greer, West Virginia. (These included acanthodians, palaeoniscoid fish, rhizodonts, lungfish, and other basal tetrapods). Beginning with this observation, I recognized a more general pattern. Wherever one Carboniferous fossil was found, one could also expect to find a whole suite of plant and/or animal fossils typical of that point in the geologic column. However, one would not find the remains of other kinds of species.
For example, when collecting fossils from Carboniferous localities in Nova Scotia, we only found the remains of plants and animals, both large and small, that were typically Carboniferous. We did not find fossilized frogs, dinosaurs, elephants, or human bones. These are found only at different points in the geologic column.
In other words, what I was beginning to discover was that all different kinds of organisms are not scattered uniformly throughout the various strata of the fossil record. Any given organism will only be found with certain other organisms, and only in certain strata.
I had been led to expect otherwise. I believed, based on creationist teaching, that all of the organisms that had ever lived (or at least all of the “Genesis kinds”) were together on earth right up until Noah’s Flood. I therefore expected that, due to the intensity of the deluge, at least some fossiliferous horizons would include a host of organisms whose co-occurrence would be completely incompatible with evolutionary expectations.
I knew roughly what these expectations were. I knew that paleontologists and geologists claimed, for example, that whale and dolphin remains are known only from sedimentary rocks of the Cenozoic Era, and that they are never mixed in with marine reptiles from the Mesozoic Era, such as plesiosaurs, ichthyosaurs, and mosasaurs. I had also heard that fossilized elephant and giraffe bones, which are also known only from the Cenozoic Era, were never found with giant sauropod dinosaur bones, which were restricted to Mesozoic strata.
Never found together? I wondered if this were true, or whether paleontologists might instead be fiddling with the evidence. Perhaps they were suppressing the knowledge of the presence of some kinds of fossils from any given locality, if those fossils posed a threat to evolutionary theory. I was therefore on the lookout for any fossils that might be conspicuously out of place with respect to their expected evolutionary time of origin and appearance within the fossil record.
Early on at McGill, I became interested in the isolated and fragmentary remains of some other vertebrates that had been collected from the quarry near Greer, West Virginia by the Cleveland Museum of Natural History and the Museum of Comparative Zoology at Harvard. These finds were too incomplete to be given formal scientific names, and remain so to this day. As I carefully removed the stone from around one of these isolated but interesting bones, it began to look more and more like the top end of a mammalian thighbone. The head of this mysterious bone had a rounded ball-like joint surface, beyond which lay several enlarged ridges for the attachment of leg muscles (so I thought), but a flattened shaft that remained embedded in the sandstone.
When my advisor, Dr. Carroll, saw what I was extracting from the stone, he knew what I was thinking, that I had found a mammalian femur in Carboniferous rocks. The fossilized remains of mammals were not supposed to occur in rocks that geologists and paleontologists identify as belonging to the Carboniferous Period. Fully mammalian critters were to that point known only from the Triassic Period, many, many millions of years after the end of the Carboniferous.
Needless to say, I was quite excited and began to keep detailed notes of the events leading to the discovery of this isolated yet important bone. I thought that I might have found evidence that would cause evolutionary biologists to question current theories on the origin of mammals and their supposed stratigraphic distribution. Realistically, I did not expect to upset the whole evolutionary apple cart with this revelation; nevertheless, I dearly wanted to throw a wrench into the works.
Of course I knew that to make such a claim, I would have to be absolutely certain that I did in fact have the hip-end of a mammalian femur! An error of this magnitude could end one’s paleontological career. And so I did some careful research to determine whether this bone might not belong after all to a creature that is typically found with Greererpeton-like tetrapods.
As I began to accumulate literature describing Carboniferous vertebrates, some of which are very poorly known, I soon discovered that the bone in question was derived from an enigmatic group of large-bodied predaceous fish known from other Carboniferous localities in the British Isles, Australia, and North America. This “mammalian” femur-like bone was in fact an upper arm bone (the humerus) of a rhizodontid fish. This curious element was correctly identified once it was freed of stone and compared with more complete fossil rhizodonts in which the humerus was still attached to the “shoulder” bones.
I quietly destroyed my notes and breathed a huge sigh of relief. (I described this bone, along with other isolated remains of rhizodontid fish from Greer, in a paper that I presented and then published as part of a symposium devoted to the study of Carboniferous faunas worldwide, which was held in Hradets Kralove, then in Czechoslovakia, now within the Czech Republic.)
Since those early days I have done a great deal more paleontological research, both in the field and in the literature, but I have yet to find a fossil that would be even remotely out of place in the stratigraphic column. So paleontologists are not “fiddling with the evidence.” Any given organism will indeed appear in the fossil record only with certain other kinds of organisms, and not with any others.