Part 4: The Transformation of Species
Alan Feuerbacher
Chapter 6 of the Creation book does a creditable job showing the improbability of the transformation between invertebrate and fish, fish and amphibian, amphibian and reptile. But on the transformation from reptile to bird and reptile to mammal the book goes completely astray. To show this we shall need to present quite a bit of information. This will also provide the background for other comments about certain other of Creation's arguments.
First, note the difference between the terms "transitional form" and "intermediate form." The former implies change while the latter implies difference. Evolutionists often use the terms interchangeably because of their belief that the one implies the other, but this implication is only their opinion. We have tried to be careful in this essay to make a distinction between the two terms if it is not clear from the context. Unfortunately Creation does not recognize the distinction and so goes to great lengths to show that because certain animals are not really intermediate in form between two major kinds of animals, such as reptiles and birds, neither are they transitional. We will show that the fossil record really does contain intermediate forms. Whether these forms are also transitional is the point of the creation/evolution controversy, and there seems little reason to take a stand on it.
One of the difficulties of Darwin's theory of evolution, and its successor, the so-called synthetic theory, is the proposed mechanism driving the change from one life form into another, namely, natural selection. Chapters 4 through 8 of Creation attempt to show this difficulty. The book presents much good evidence, but makes many misstatements and leaves gaps in the reader's understanding of the issues. We will here point out some of these problems.
First, the following quotation summarizes the scientific consensus on transitional life forms.58 Keep in mind that creationists claim no transitional species have ever been found.
... it is worth noting how the various vertebrate classes actually appear in the fossil record. As noted, the first amphibian is the most fishlike of all amphibians. The first true reptiles? These can be seen in a group where amphibian and reptilian characteristics are mixed, known as Seymouria. Here again, the first known reptiles are remarkably amphibian in character. The pattern is repeated in the development of birds, where the first known complete skeletons, including the remarkable fossils of Archaeopteryx, are completely intermediate in character, and some specimens would in fact actually have been classified as reptiles but for the lucky fact that certain fossils were found with preserved feather impressions.
'Indeed, if feather impressions had not been preserved, all Archaeopteryx specimens would have been identified as coelurosaurian dinosaurs. The only reasonable conclusion is that Archaeopteryx must have been derived from an early or mid-Jurassic theropod.' [J. H. Ostrom, Nature, 242(1973):136]
Finally, there is a remarkable evolutionary series of fossils connecting reptiles and mammals. Is this final series represented by a single intermediate which the creationist may insist is not quite intermediate enough? Not at all:
'... the mammals almost universally offer sharp and obvious contrasts to the reptiles. But in the Permo-Triassic sequence of fossils the contrasts were established only slowly and gradually through groups of intermediates, and became indefinite in the earlier members of the theromorphs so that "what is a mammal and what is not a mammal is pretty much an academic question..."' [T. N. George, Sci. Prog. Ox, 189(1960):13.]
The transition between reptiles and mammals is filled by nearly a dozen intermediates, and the case for evolution is stronger with every new fossil discovered in the rocks of this period. Here we have the first and most direct response to the creationist criticism of the fossil record. Intermediate forms do exist, there are thousands of them, and we can tell the public what they are, why they are "intermediate," and show that however bold the creationist attacks are, they are totally wrong at the level of the fossil record itself. However, there is a more telling point to be made here, and this point has to do with the alternative theory the creationists are attempting to establish.
If we were to accept creationist criticism of the fossil record at its face value, what scheme could we then propose for the natural history of this planet? Accepting the premise of divine creation and the impossibility of evolution, we would have to suggest that a creator formed the first jawless vertebrates some 600 million years ago by an act of special creation, so that these animals appeared suddenly and without ancestors. Nearly all these jawless forms died out shortly after being created, and those that do survive are quite different. Some in fact survive by parasitizing species of fish that did not appear until some 200 million years after the jawless fishes were specially created, a curious fact indeed. Then, nearly 100 million years later the creator made bony fishes, somewhat like the kinds which now occupy the oceans. Later he specially created primitive amphibians, stepping in again and again over the next 50 million years to create the many amphibian groups which appear and then disappear in the fossil record. Still later, he formed primitive birds and primitive mammals, intervening again and again to carry out a series of special creation events so closely graded that the scientists of the present would misinterpret these progressive appearances and disappearances as the result of evolutionary change and extinction. Is this scheme of a progressive creator acting over millions of years the alternative explanation of natural history which the creationists would like to open our minds to? Not at all.
Another book commented on creationist's statements that no transitional fossils have ever been found:59
We have found clear evidence of transitional links between major vertebrate groups ... We have found sources in Pre-Cambrian rocks for the famous Cambrian explosion of multicellular life forms... We have found primitive antecedents of the flowering plants -- links between the angiosperms and the gymnosperms that dominated the land before angiosperms appeared sometime in the Cretaceous... We have found links between modern humans and fossil apes... In many cases, the problem is not a lack of intermediates but the existence of so many closely related intermediate forms that it is notoriously difficult to decipher true ancestral-descendant relationships. In a very real sense, the fossil record is far better testimony to evolutionary change than Darwin, in his later years, probably imagined possible.
So the general scientific consensus is that there are definitely transitional forms in the fossil record. Whether they really are transitional or not, they are definitely intermediate, in that they show characteristics of two kinds of creatures. Such creatures are termed mosaics.
In view of the above statements from scientists concerning transitional forms, which we will call intermediate forms, Creation's statements in paragraphs 14 and 15 on page 59 are incomplete and misleading:
What has confounded such scientists is the fact that the massive fossil evidence now available reveals the very same thing that it did in Darwin's day: Basic kinds of living things appeared suddenly and did not change appreciably for long periods of time. No transitional links between one major kind of living thing and another have ever been found. So what the fossil record says is just the opposite of what was expected.
Swedish botanist Heribert Nilsson described the situation this way, after 40 years of his own research: "It is not even possible to make a caricature of an evolution out of palaeobiological facts. The fossil material is now so complete that... the lack of transitional series cannot be explained as due to the scarcity of material. The deficiencies are real, they will never be filled."
Creation quoted Heribert Nilsson's 1953 book. Much fossil evidence has been found since 1953 that makes his statements out of date. We will shortly show examples of this.
This quotation seems to be another example where Creation got its reference from Francis Hitching's The Neck of the Giraffe, although here, at least, the quotation actually seems to have been checked against the original source. The quotation is identical to that in Hitching (p. 11 paperback) except for the ellipses, which Hitching left out. Hitching's reference for the publishing date for Nilsson's book is 1954, and he gives no page number, whereas Creation does give the page.
Now let's get down to specifics. The section of Creation beginning on page 64, "No Transitional Features," clearly shows how Creation leaves out or obscures pertinent information. Paragraph 29 says:
New Scientist noted that evolution "predicts that a complete fossil record would consist of lineages of organisms showing gradual change continuously over long periods of time." But it admitted: "Unfortunately, the fossil record does not meet this expectation, for individual species of fossils are rarely connected to one another by known intermediate forms... known fossil species do indeed appear not to evolve even over millions of years."
Note carefully that New Scientist noted that species are rarely connected by intermediate forms. This is quite different from never connected. Paragraph 29 from Creation continues:
And geneticist Stebbins writes: "No transitional forms are known between any of the major phyla of animals or plants." He speaks of "the large gaps which exist between many major categories of organisms."
Creation is here speaking of transitional forms between species and transitional forms between phyla as if they were equivalent. Its author does not seem to know the difference between a phylum and a species. A phylum is a major subdivision within the plant or animal kingdoms. For example, arthropods (crustaceans, insects, spiders) are one phylum and chordates (animals with spinal cords) are another. Since the first discoveries of early Cambrian fossils it has been evident that these phyla have been distinct since their origins, and evolutionists do not state otherwise. A species is a narrowly defined category of animal. A wolf is classed as a different species from a dog, for example, even though sometimes the distinction is not clear.
The context of the quotation from Stebbins shows that what he said regarding what he called transitional forms between, and the origin of, various categories of animals, is exactly opposite to what is implied by Creation:60
If categories become well defined because forms intermediate between them become extinct, then in the history of groups having a good fossil record we should be able to find periods when categories which are now well defined were connected by transitional forms. If we analyze the fossil record of vertebrates, this is exactly what we see. Among modern animals, the dog and bear families are regarded as definitely related to each other, but even when all contemporary members of the two families are considered, nobody has any difficulty in distinguishing bears from dogs, foxes, and coyotes. In the Miocene and early Pliocene epochs, however, the situation was different. At that time, animals intermediate between dogs and bears were common, so that paleontologists have great difficulty in deciding just when the dog and bear families became distinct from each other...
Going farther back in the fossil record, we learn that in the latter part of the Eocene epoch, primitive animals which are now clearly recognized as forerunners of the principle families of carnivores: dogs, cats, weasels, civets, and their relatives, were linked together by a complex network of resemblances...
There are... many differences between modern reptiles and amphibia in the structure of their skeletons, and these have been used by paleontologists for recognizing the first reptiles to appear. An eminent paleontologist, A. S. Romer, remarks of these animals: "Primitive Paleozoic reptiles and some of the earliest amphibians were so similar in their skeletons that it is almost impossible to tell when we have crossed the boundary between the two classes."...
In respect to the early evolution of mammals, the same situation exists. The distinctive characteristics of modern mammals; warm blood, hair, and the ability to suckle their young, cannot be determined in fossils. In respect to their skeletons, however, modern reptiles are, and the dinosaurs were, very different from modern mammals. On the other hand, the animals which dominated the land in the later Permian and early Triassic Periods, before the dinosaurs appeared, were the mammal-like reptiles or therapsids, which in both their skulls and teeth were almost halfway between typical reptiles and primitive mammals...
During the Triassic Period, the therapsids gave rise to several groups of rather small, light-boned and active reptiles, which because of their specialized teeth were known as the "dog tooths" (cynodonts)... These animals existed for more than twenty million years during the latter half of the Triassic Period. Their skeletons were mammal-like in most respects, except that they had not yet acquired the three mammalian ear bones... the counterparts of two of them (quadrate and articular) were still part of the lower jaw... Recently discovered skulls indicate that the shift from jaw to ear bones took place gradually. Commenting on this situation, an eminent paleontologist, E. H. Colbert, remarks: "All of which indicates how academic is the question of where the reptiles leave off and the mammals begin."...
The first true mammals appeared in the late Triassic Period, about the time when the cynodonts were becoming extinct. The age of dinosaurs began later, during the Jurassic Period. During the entire period when the earth was dominated by these reptilian giants, small active mammals existed side by side with dinosaurs.
These facts tell us that the transition from reptiles to mammals was very gradual, taking place over a period of approximately 100 million years. It took place simultaneously with the beginning of the major adaptive radiation of the reptiles themselves. Mammals are simply a further extension, through directional evolution, of one particular radiant line of reptiles.
The transition from reptiles to birds is more poorly documented than are the other transitions between classes of vertebrates. Nevertheless, many of the smaller reptiles in the group ancestral to dinosaurs and crocodiles had light skeletons from which those of birds could have arisen, and moreover walked exclusively on their hind legs, as do birds. Furthermore, the earliest fossil birds, from Jurassic deposits of Germany, had jaws containing teeth and forelimbs with well developed fingers... We classify them as birds because feathers are preserved with their skeletons; but if their preservation had been somewhat poorer and the feathers were not present, these animals might well have been classified as reptiles.
Thus the fossil record of vertebrates strongly suggests that the characteristics which distinguish the modern higher categories appeared first as distinctive features of certain species or genera. They became characteristics of families, orders, and classes only after descendants of the animals which first possessed them developed them further, radiated into numerous adaptive niches, and became separated from other groups by extinction of intermediate forms. In other groups of organisms such as insects and higher plants, in which the fossil record is far more fragmentary, profound gaps exist between many orders, suborders, and classes. Furthermore, no transitional forms are known between any of the major phyla of animals or plants. In view of the incompleteness and biased nature of the fossil record in all of these groups, and the extremely long time, measured in hundreds of millions of years, since the various phyla of organisms evolved, the large gaps which exist between many major categories of organisms aside from the vertebrates are most reasonably ascribed to known imperfections in the fossil record...
A further point must be emphasized in connection with the evolution of families, orders, and classes. This is its "mosaic" character. As pointed out in connection with both the evolution of amphibia from fishes and of mammals from reptiles, the various characteristics which now distinguish the more evolved class probably evolved separately, some relatively early, others much later, at periods of evolutionary time which in some instances were separated from each other by millions of years...
Consequently, we cannot speak of any single "step" in the evolution of mammals from reptiles. In some instances, such as the change in position of the jaw bones to the ear, a relatively small number of genetic changes may have triggered off the evolution and establishment of a new adaptive complex with respect to that particular character... These changes would however, have occurred at the level of subspecies or closely related species. A contemporary taxonomist, transported to the Mesozoic era and not knowing anything about the evolutionary future, would probably have classified the first population bearing all three bones; hammer, anvil and stirrup, in its middle ear, as an aberrant species belonging to the then widespread group of therapsid reptiles. As stated above, this group probably already possessed a mixture of characters which we now associate on the one hand with reptiles and on the other with mammals.
So Stebbins actually said, with regard to what Creation quoted, that in contrast with the fairly complete record of vertebrate evolution, which shows numerous intermediate forms, the fossil record of transitional forms between major categories (phyla) of animals and plants is very poor and often shows nothing. This is not at all the same as what Creation implies, which is that no intermediate forms exist at all. Again the author of Creation argues as does a literary critic.
The fact that Creation's author is confused about the difference between phyla and species is further shown by the fact that, immediately after he quotes Stebbins about phyla and major categories of animals, paragraph 29 says:
"In fact," The New Evolutionary Timetable acknowledges, "the fossil record does not convincingly document a single transition from one species to another. Furthermore, species lasted for astoundingly long periods of time."
This is again a quotation out of context. The New Evolutionary Timetable was talking about fossil finds in the Big Horn Basin of Wyoming, when it said:61
Superb fossil data have recently been gathered from deposits of early Cenozoic Age in the Bighorn Basin of Wyoming. These deposits represent the first part of the Eocene Epoch, a critical interval when many types of modern mammals came into being. The Bighorn Basin, in the shadow of the Rocky Mountains, received large volumes of sediment from the Rockies when they were being uplifted, early in the Age of Mammals. In its remarkable degree of completeness, the fossil record here for the Early Eocene is unmatched by contemporary deposits exposed elsewhere in the world. The deposits of the Big Horn Basin provide a nearly continuous local depositional record for this interval, which lasted some five million years. It used to be assumed that certain populations of the basin could be linked together in such a way as to illustrate continuous evolution. Careful collecting has now shown otherwise. Species that were once thought to have turned into others have been found to overlap in time with these alleged descendants. In fact, the fossil record does not convincingly document a single transition from one species to another. Furthermore, species lasted for astoundingly long periods of time. David M. Schankler has recently gathered data for about eighty mammal species that are known from more than two stratigraphic levels in the Big Horn Basin. Very few of these species existed for less than half a million years, and their average duration was greater than a million years.
This is all said within the framework of author Steven M. Stanley's attempt to show that the "punctuated equilibrium" model of evolution is correct, rather than the traditional gradualist model. The fact that there are serious difficulties with either theory does not change the fact that Creation has incorrectly applied the quotation to the fossil record as a whole, when the context so clearly limits its application to the Big Horn Basin. That Stanley's intent is so limited is shown by his later statement:62
A frequent claim of creationists is that the fossil record contradicts [the] concept of evolution. One argument here is that there are no transitional forms between distinctive groups of animals or plants. This is not true, and what is most important is that evolutionists do not need dozens of examples to make their case... Quoting certain scientists who have claimed Archaeopteryx to be fully birdlike, creationists have dismissed this interesting form as meaningless, but they are only telling a half-truth. Other scientists have claimed Archaeopteryx to be remarkably dinosaurian -- to be a dinosaur with a wishbone and feathers! This disagreement is no embarrassment to evolution. Quite the reverse. It underscores the transitional character of the famous fossil. Archaeopteryx represents a single intermediate form. Elsewhere, despite the punctuational nature of many transitions, we have available series of forms that more fully represent steps in the origins of certain major groups.
A statement by the "dean of American Paleontologists," George Gaylord Simpson, well sums up the state of knowledge of the fossil record as of 1961:63
The record already acquired is amazingly good. It provides us with many detailed examples of a great variety of evolutionary phenomena on lower and intermediate levels and with rather abundant data that can be used either by controlled extrapolation or on a statistical sampling basis for inferences as to phenomena on all levels up to the highest. Among the examples are many in which, beyond the slightest doubt, a species or a genus has been gradually transformed into another. Such gradual transformation is also fairly well exemplified for subfamilies and occasionally for families, as the groups are commonly ranked... In spite of these examples, it remains true, as every paleontologist knows, that most new species, genera, and families and that nearly all new categories above the level of families appear in the record suddenly and are not led up to by known, gradual, completely continuous transitional sequences.
Again it is evident that although most new forms of life appear suddenly in the fossil record, there are many examples of what appear to be gradual transitions. Any discussion leaving out this information is incomplete and misleading.
Creation again quotes out of context and misapplies what an author said in paragraph 37, on page 70:
"The concept of evolution cannot be considered a strong scientific explanation for the presence of the diverse forms of life," concludes evolutionist Edmund Samuel in his book Order: In Life. Why not? He adds: "No fine analysis of biogeographic distribution or of the fossil record can directly support evolution."
What Samuel was discussing was more subtle than the author of Creation realized. He was discussing how humans can bring order to general systems of thought, and discussing the fact that some systems can be shown to be self-consistent in a logically strong or logically weak sense. His use of "strong," therefore, is not in the absolute sense implied by Creation, but rather in the sense used by philosophers in evaluating logical arguments. Logical arguments may have bearing on reality or may not. Certain arguments in mathematics may have little or no present bearing on reality but can be evaluated rigorously by logical methods. Reconstructing the scene of a crime is a very different sort of logical process, and is the sort Samuel is talking about with respect to evolution. Here is a more complete version of what he said:64
... on the whole, evolution has been extremely beneficial in ordering our thoughts. On the other hand, the concept of evolution cannot be considered a strong scientific explanation for the presence of the diverse forms of life in space and time. It must remain as a rather low level explanation to any purist. This is because the data must be used circumstantially and no fine analysis of biogeographic distribution or of the fossil record can directly support evolution. Biogeographic data are so complex that even with island studies only the rough generalities similar to those Darwin found for Galapagos can be stated. The fossil record is very uneven and so scarce that fine points regarding the pathways of evolution remain obscure...
If there is no regularity in these historical records, what is their meaning and where are they going? Are there any characteristics that somehow influence the directions of change? One can say that in general the biomass has increased, the numbers and kinds of species have increased, organisms have increased in complexity in terms of number and diversity of cell types, and food-webs have become more complex. There are always those cases, however, that violate each of these general statements, e.g., extinction, degeneracy, and man's cultivated fields...
Perhaps the greatest contribution of the fossil record to the support of the concept evolution is the absence of negative observations. If a mammal could be dated with certainty at 500 million years, the concept would suffer considerably. The weakness of the concept (as a scientific explanation) makes it extremely vulnerable. The fact that exceptions of this sort have not held up under careful scrutiny, and the fact that there is a tremendous amount of circumstantial evidence that is consistent within itself means that the explanation is still a good one though it may not satisfy the purists...
... With all due respect for [Darwin's] attempt [to provide a logical mechanism for evolution], and even in spite of the fact that natural selection has been successfully tested as a means to modify species, there remains a major difficulty for our search. Even if natural selection is proved to be a way in which evolution could have occurred, it does not prove that it was the way or the only way that it did occur. No mechanism can stand alone without applying it in a test to the actual phenomenon the mechanism is supposed to produce. This is impossible to do and so the mechanism itself must remain as circumstantial evidence -- to the purist.
My point is that apparently different explanations can have different values. Evolution and natural selection may not explain in a certain way the presence of diverse living and fossil forms of life, but it is still a good explanation, at least until something better comes along.
What all this means is that since no human was there to observe and record the history of life, any explanation based on the fossil record, of how life came about, will always be based on circumstantial evidence. This is because there can always be more than one reasonable explanation that fits circumstantial evidence. This sort of philosophical problem does not prevent police from solving crimes or prevent anyone from making many valid conclusions based on circumstantial evidence. Creation's author entirely misses the point.
From the above examples it is clear that Creation constantly uses out-of-context quotations to support its contention that no intermediate or transitional life forms are found in the fossil record. Paleontologist Stephen Jay Gould said about this practice:65
Faced with these facts of evolution and the philosophical bankruptcy of their own position, creationists continually rely upon distortion and innuendo to buttress their rhetorical claim. If I sound sharp or bitter, indeed I am -- for I have become a major target of these practices...
I count myself among the evolutionists who argue for a jerky or episodic, rather than a smoothly gradual, change of pace. In 1972, my colleague Niles Eldredge and I developed the theory of punctuated equilibrium... We proposed the theory of punctuated equilibrium largely to provide a different explanation for pervasive trends in the fossil record. Trends, we argued, cannot be attributed to gradual transformation within lineages... Since we proposed punctuated equilibria to explain trends, it is infuriating to be quoted again and again by creationists -- whether through design or stupidity, I do not know -- as admitting that the fossil record includes no transitional forms. The punctuations occur at the level of species; directional trends... are rife at the higher level of transitions within major groups. Yet a pamphlet entitled: "Harvard Scientists Agree Evolution Is a Hoax" states: "The facts of punctuated equilibrium which Gould and Eldredge... are forcing Darwinists to swallow fit the picture that Bryan insisted on, and which God has revealed to us in the Bible."
Continuing the distortion, several creationists have equated the theory of punctuated equilibrium with a caricature of Goldschmidt's belief that major transitions are also accomplished suddenly by means of "hopeful monsters."
Anthropologist Laurie R. Godfrey had this to say about the usual style of argument of creationists:66
Field or laboratory research represents a very minor charge of scientific creationists. Most efforts are directed toward rewriting the discoveries and interpretations of evolutionists. In this endeavor, numerous evolutionists are portrayed as scientists who have all the evidence to disprove evolution (and support creation) at their fingertips, but who are either too stubborn or too deeply indoctrinated in evolutionary dogma to appreciate it. Arguments of anthropologists, biologists, chemists, geologists, astronomers, physicists, and engineers are reinterpreted or taken out of context. In this way, as I will show below, creationists manage, among other things, to convert arguments about the pattern and process of evolutionary change into arguments about the existence of change.
The primary tactic of the scientific creationists is to find controversy, disagreement, and weakness in evolutionary theory -- by no means a difficult task. Having demonstrated problems with various aspects of evolutionary theory (some fabricated, some real), the creationists then conclude that we must accept the Judeo-Christian biblical account of creation as the only possible, logical alternative. Thus scientific creationism proceeds by constructing an artificial dichotomy between two models -- evolution and creation -- both incorrectly represented as monolithic...
Creationists are decidedly uninterested in the merits of any of these arguments [about evolutionary mechanisms] and, indeed, in the issues themselves. But they are interested in convincing the public that the concept of evolution is utterly bankrupt. By citing and falsely reinterpreting excerpts from a vast and complex scientific literature, they have built for their constituency a false (though superficially plausible) picture of what the issues really are. Furthermore, since most laypersons equate Darwinism with evolution, critics of neo-Darwinism are especially vulnerable to misrepresentation. But the non-Darwinian arguments so often cited by creationists can hardly be taken as support for creationism by anyone who bothers to discover what they are really about.
The Creation book well illustrates the style of argument described above. Although the Society adamantly insists it is not among the ranks of scientific creationists, Godfrey has well described how its publications often argue. As we've shown above it is clear its writers have not bothered to find out what the arguments really are about with regard to transitional forms of life. Godfrey continues:67
[Stephen Jay] Gould and his colleagues are widely cited by creationists in their effort to establish that the fossil record documents "no transitions." To creationists this is taken to mean that there are no evolutionary links between "created kinds." But Gould, Eldredge and Stanley are talking about the failure of the fossil record to document fine-scale transitions between pairs of species, and its dramatic documentation of rapid evolutionary bursts involving multiple speciation events -- so-called adaptive radiations. They are not talking about any failure of the fossil record to document the existence of intermediate forms (to the contrary, there are so many intermediates for many well-preserved taxa that it is notoriously difficult to identify true ancestors even when the fossil record is very complete). Nor are Gould, Eldredge, and Stanley talking about any failure of the fossil record to document large-scale trends, which do exist, however jerky they may be. Furthermore, fine-scale transitions are not absent from the fossil record but are merely underrepresented. Eldredge, Gould, and Stanley reason that this is the unsurprising consequence of known mechanisms of speciation. Additionally, certain ecological conditions may favor speciation and rapid evolution, so new taxa may appear abruptly in the fossil record in association with adaptive radiation. Since creationists acknowledge that fine-scale transitions (including those resulting in reproductive isolation) exist, and since the fossil record clearly documents large-scale "transitions," it would seem that the creationists have no case. Indeed, they do not. Their case is an artifact of misrepresentation to the lay public of exactly what the fossil record fails to document.
What does the fossil record actually show with regard to how gradual or abrupt the change of life forms is through time? It shows both gradual and abrupt change. For example, an extensive fossil bed related to the famous Olduvai Gorge in Africa yielded a great deal of information:68
In 1967 there commenced a large-scale international investigation of the highly fossiliferous deposits along the Omo River in southern Ethiopia. Over 50 tonnes of fossils were collected from a sequence of deposits over 1000 metres thick and covering the time-span from 4 million years ago, almost to the present day -- completely bridging the time gap between Olduvai and Lateoli. The mammalian faunas show a striking change during this time, though this appears to be predominantly a gentle transformation resulting from progressive evolution, with no real faunal breaks. Interesting mammals in the lowest levels are Anancus (a mastodon), Stegodon and Hexaprotodon, a hippopotamus with six (three pairs of) incisors in the upper and lower jaws. The hippopotamus in the later part of the sequence is H. gorgops, already noticed at Olduvai, which is of different ancestral stock and which has two pairs of incisors in the upper jaw and only one in the lower. Several of the groups of mammals, most notably the horses and rhinoceroses, show a trend from the earlier to later strata towards more high-crowned teeth, interpreted, with other lines of evidence, as an indication of a change of climate from wet to less wet and of the ecological setting from bush and scrub and of tall grass to more open savannah and shorter grass. Important hominid finds include an australopithecine of gracile appearance in the lower part of the sequence and a robust australopithecine appearing about two million years ago.
Regarding many more specific details of what has been found, an article by paleontologist Roger J. Cuffey said:69
... we can examine the fossils entombed in chronologically successive rock layers, and thereby learn what organisms inhabited this planet during successive intervals of past geologic time. When we do this, we find that the fossils naturally form sequences showing gradual and continuous morphologic changes from earlier forms to later forms of life, sequences which make evolutionary interpretations ultimately inescapable.
As working paleontologists interested in the history of particular organisms, we locate for detailed study a relatively thick succession of fossil-bearing rock layers whose observable physical features indicate continuous and uninterrupted deposition over a comparatively long time interval. We next examine those layers for the fossils in which we are interested. We initially find a few fossils, scattered widely among the different layers. Studying these specimens usually shows noticeable morphological differences between ones from various geologic ages, differences which we recognize formally in progress reports by referring the specimens to different species, genera, etc., depending upon the magnitude of those differences. Continued field collecting from the rock strata intervening between any two successive forms thus described frequently produces a series of fossils which begin with the earlier form, change in morphology gradually and continuously as we proceed upward, and end up with the later form. Because these new fossils demonstrate a morphological and parallel chronological transition from the earlier form to the later form, they are termed "transitional fossils."
If we read the paleontologic literature (especially if with the background of professional paleontologic training and experience...), we find that the fossil record contains many examples of such transitional fossils. These connect both low-rank taxa (like different species) and high-rank taxa (like different classes), in spite of the record's imperfections and in spite of the relatively small total number of practicing paleontologists. Because of the critical role which transitional fossils played in convincing scientists of the occurrence of organic evolution, paleontologists have been appalled that many otherwise well-informed persons have repeated the grossly misinformed assertion that transitional fossils do not exist. Consequently, after a relatively brief and non-exhaustive search of the literature immediately available to me, I compiled the examples of transitional fossils presented here. At least enough of these can be readily examined by anyone seriously interested in this topic that he can be convinced of their implications, I believe; collectively, they (and the many other similar ones which more extended search would find) comprise a massive body of evidence which cannot be ignored or explained away.
Although the broad patterns and many details in the history of life are well known, many other details remain to be learned. Because of the unevenness of our knowledge, therefore, we can conveniently distinguish several different types of transitional-fossil situations. Let us consider these now, starting with that situation where our knowledge is most complete, and proceeding through situations in which knowledge is progressively less complete.
First, some groups have been so thoroughly studied that we know sequences of transitional fossils which grade continuously from one species to another without break (Table 1), sometimes linking several successive species which cross from one higher taxon into another (Table 2). We can say that situations of this kind display transitional individuals. Among the many available examples of transitional individuals, some particularly convincing examples can be noted. These involve:
The author then lists, with source references: corals, gastropods, pelecypods, and echinoids. In Table 1, "Examples of transitional individuals grading continuously between successive species within the same higher taxon (genus)", he lists algae, angiosperms, foraminiferans, corals, bryozoans, brachiopods, gastropods, pelecypods, ammonoids, trilobites, echinoids, conodonts, and mammals. In Table 2, "Examples of transitional individuals grading continuously between successive species, and crossing from one higher taxon into another", he lists ginkgophytes, angiosperms, foraminiferans, brachiopods, pelecypods, ammonoids, conodonts, mammals, and hominids.
Second, other fossil groups have been well enough studied that we know sequences of transitional fossils comprising a series of chronologically successive species grading from an early form to a later form (Table 3), again sometimes crossing boundaries separating different higher taxa (Table 4). This type of situation can be termed successive species. Published descriptions of successive species lack explicit discussion of individuals transitional between the species, although frequently such exist in the author's collection but are not discussed because they are not directly pertinent to his purposes. Again, some especially persuasive examples of successive species can be seen, among:
Cuffey then lists, with source references: foraminiferans, brachiopods, pelecypods, and ammonoids. In Table 3, "Examples of successive species within the same higher taxon (genus)", Cuffey lists angiosperms, foraminiferans, brachiopods, gastropods, pelecypods, trilobites, crustaceans, carpoids, blastoids, graptolites, fishes, amphibians, and mammals. In Table 4, "Examples of successive species crossing from one higher taxon into another", he lists ginkgophytes, foraminiferans, bryozoans, gastropods, pelecypods, nautiloids, ammonoids, crustaceans, crinoids, echinoids, reptiles, reptile-mammal transition, and mammals.
Cuffey goes on to provide much more information on examples of transitional forms and other things pertinent to this essay. Cuffey's article should be read by anyone attempting to discuss the existence of transitional forms, as it provides much information not normally available to those outside the paleontological profession.
As shown above, in some cases a series of fossils is found that is consistent with the continuous gradual change that Charles Darwin predicted in his theory of evolution, but species much more often remain stable for long periods of time. Many evolutionists are coming to grips with the fact that the evidence for Darwin's theory of progressive gradual change of one species into another is not generally found in the fossil record. Darwin also realized this and postulated that the fossil record was too poor to show the transitional forms he expected. He predicted that ultimately these forms would be found.
Within the last two decades many evolutionists have given credence to the theory of punctuated equilibrium. This theory was first advanced in 1972 by Stephen Jay Gould and Niles Eldredge, in an attempt to account for the lack of evidence of gradual change while retaining the basic notion that evolution had occurred and could be explained. Niles Eldredge, in The Myths of Human Evolution, said of the search for these forms since Darwin's time:70
Paleontologists just were not seeing the expected changes in their fossils as they pursued them up through the rock record. Instead, collections of nearly identical specimens, separated in some cases by 5 million years, suggested that the overwhelming majority of animal and plant species were tremendously conservative throughout their histories... it has become abundantly clear that the fossil record will not confirm this part of Darwin's predictions. Nor is the problem a miserably poor record. The fossil record simply shows that this prediction was wrong.
The observation that species are amazingly conservative and static entities throughout long periods of time has all the qualities of the emperor's new clothes: everyone knew it but preferred to ignore it. Paleontologists, faced with a recalcitrant record obstinately refusing to yield Darwin's predicted pattern, simply looked the other way. Rather than challenge well-entrenched evolutionary theory, paleontologists tacitly agreed with their zoological colleagues that the fossil record was too poor to do much with beyond supporting, in a general sort of way, the basic thesis that life had evolved. Only recently has a substantial number of paleontologists blown the whistle and started to look at the evolutionary implications of the marked pattern of nonchange -- of stability -- within species so dominant in the fossil record of life.
... in the vast majority of cases... [species] have remained substantially unchanged through monumentally long periods of time. Species, in other words, seem to be relatively static. There is frequently more variation throughout the geographic spread of a species at any one point in time than will be accrued through a span of 5 million or 10 million years.
This observation has two simple consequences, both of tremendous importance to evolutionary theory. First, Darwin's prediction of rampant, albeit gradual, change affecting all lineages through time is refuted. The record is there, and the record speaks for tremendous anatomical conservatism. Change in the manner Darwin expected is just not found in the fossil record.
The second simple consequence is the observation that species are stable and remain discrete, in time as well as space. They are individuals in the true sense of the word: they have beginnings, histories, and, ultimately, ends.
So species themselves tend to remain stable, but what about all the change that is supposed to have occurred? The Myths of Human Evolution says:71
... the overall picture presented by the fossil record confirms the most basic predictions we can make to test the very notion of evolution: if all organisms are related by a process of ancestry and descent, older rocks should contain more primitive members of a group than younger rocks. We should be able to document progressively more advanced forms as we look in correspondingly younger rocks. This is what we find.
But this very confirmation of the most basic of evolutionary predictions has led us astray. As we have seen in the previous chapter, the usual conception casts evolution as a gradual, steady process of adaptive change. And we have already seen that the fossil record conflicts with that view. Now let's look at the fossil record to see what patterns of evolutionary change are actually there. The general agreement that older rocks produce more primitive fossils and that as we look in younger rocks we usually find more advanced members of an evolving lineage has been taken as sufficient evidence that the evolution of life is fundamentally a process of gradual, progressive, adaptive change. But when we take a second, harder look at the fossil record we begin to see the truly mythic qualities of this story. For the gross patterns of evolutionary change so abundantly documented in the fossil record could have been produced in a number of different ways. We are faced more with a great leap of faith -- that gradual, progressive, adaptive change underlies the general pattern of evolutionary change we see in the rocks -- than any hard evidence. In fact, a closer look at the fossil record shows that another view, centering around the evolution, stability, and death of individual species, predicts a pattern of change that fits the facts of the fossil record much more closely.
The notion of gradual, progressive change collides head-on with the stability seen in most fossil species, for the general progressive sequence of life's evolutionary history seen in the fossil record has always been taken as confirmation of the underlying assumption that all change comes from progressive generation-by-generation modification of species. What the record is really telling us is that evolution, as suspected, has occurred. But we have greatly erred in predicting what the pattern of change should look like in the fossil record. Rather than taking the record literally, we have dismissed the lack of change within species as merely the artifacts of an imperfect record. But the time has come to ask, instead, if the record isn't telling us something that our theories ought to be able to explain -- rather than explain away.
Summarizing Eldredge's statements, the fossil record shows clear trends from species to species, but little evidence of change within species. Eldredge proposes that the theory of punctuated equilibrium accounts for the observations.
Some creationists misrepresent Eldredge and Gould's theory by claiming that they now reject evolution, or that their work shows no transitional forms have been found in the fossil record. Anthropologist Laurie Godfrey showed this is not the case:72
In 1972 Niles Eldredge of the American Museum of Natural History and Harvard paleontologist Stephen Jay Gould launched their new theory of evolution by "punctuated equilibria" in an attempt to explain the rarity, not absence, of transitional forms at the species level. Evolution, they said, commonly proceeds in fits and starts punctuating relatively long periods of evolutionary stasis. Ironically, Eldredge (1971) first arrived at his notion of punctuated equilibria while studying Devonian trilobites whose excellent fossil record includes intermediates at this fine level of evolutionary change. Gould (1969) similarly studied an excellent record of spatial and temporal variation in a Pleistocene land snail from Bermuda, Poecilozonites. It was the restricted temporal and geographic distribution of morphological intermediates and the pattern of occurrence of morphological innovations that convinced first Eldredge and then Gould that Darwin had been wrong in one important aspect of his theory of evolutionary change: his pervasive gradualism... Eldredge and Gould posited a biological explanation of gaps in the fossil record, the strength of which lay in its ability to simultaneously account for two prominent features of the fossil record: (1) relatively long periods of stasis in some well-documented fossil species; and (2) intermittent interruptions of stasis by brief intervals of rapid evolution (often represented by gaps in the fossil record). Both stasis and rapid evolution, they reasoned, could be explained by the notion, already current in the neontological literature, that rapid morphological innovations occur in small "founder" populations often in conjunction with the evolution of reproductive barriers separating the founder populations from the parent populations. If successful, these innovations can lead to the growth and establishment of a "daughter" species or even to the eventual replacement of the mother species by the daughter species. This idea is decidedly non-Darwinian. That splitting of lineage (or "speciation") contributes significantly to morphological evolutionary change can be found nowhere in Darwin's work...
Eldredge and Gould (1972) agreed that a perfect fossil record would document morphological intermediates between species, but they suggested that many of these would exhibit relatively brief and geographically limited existences. Indeed, Eldredge had such a near perfect record of the evolution of the Devonian trilobite Phacops. It was a record of stepwise evolutionary change in only two brief intervals during a span of eight million years! One such interval was recorded in a single easy-to-miss quarry in New York State. This quarry contained perfect intermediates between the geographically widespread mother and daughter species. In effect, due to the realities of an imperfect fossil record, most such intermediates will simply not be sampled.
Punctuated equilibrium has problems, however, since it does not explain the mechanism of the larger scale changes, but in essence, merely acknowledges that this sort of change exists.
From the preceding quotations about what the fossil record shows, it should be evident that a clear consensus does not exist on the details of what changes in life forms occurred. Sometimes the changes appear abrupt and sometimes they appear gradual. However, a consensus does exist that there is much change evident in the record, and that intermediate forms exist.
The impression can be gotten that there is available to the Society's writers a file of short quotations on evolution, from a large variety of sources, many probably sent in by readers. A good speculation would be that the quotations are short excerpts of material that can be interpreted as critical of various aspects of evolution. They are probably often too short for the writers to get the sense of what the references actually say. The writers would be unable, even if they were willing, to use the quotations properly. The problem becomes especially acute when old, out-of-date sources are used without checking the current state of knowledge.
Footnotes
58 Ashley Montagu, ed., op cit, pp. 51-52.
59 Laurie R. Godfrey, Scientists Confront Creationism, pp. 198-199, W. W. Norton & Company, New York, 1983.
60 G. Ledyard Stebbins, Processes of Organic Evolution, pp. 142-148, Prentice-Hall, Inc., Englewood Cliffs, New Jersey, 1971.
61 Steven M. Stanley, The New Evolutionary Timetable, p. 95, 1981.
62 ibid, pp. 174-176.
63 George Gaylord Simpson, The Major Features of Evolution, pp. 359-360, Columbia University Press, New York, 1961.
64 Edmund Samuel, Order: In Life, pp. 120-122, 1972.
65 Ashley Montagu, ed., Science and Creationism, pp. 123-124, Oxford University Press, New York, 1984.
66 ibid, pp. 170-171.
67 ibid, pp. 177-178.
68 Antony J. Sutcliffe, On The Track Of Ice Age Mammals, p. 163, Harvard University Press, Cambridge, Massachusetts, 1985.
69 Ashley Montagu, ed., Science and Creationism, pp. 256-265, Oxford University Press, New York, 1984.
70 Niles Eldredge & Ian Tattersal, The Myths of Human Evolution, pp. 45-48, Columbia University Press, New York, 1982.
71 ibid, p. 57.
72 Laurie R. Godfrey, ed., op cit, p. 205.
