Part 4: The Details of the Fossil Record: Evidence Against Macroevolution

Introduction
Part 1
Part 2
Part 3

More on the series on Evolution with Dr. Jay Wile and Marilyn Durnell...

Word count: 3,238
Estimated reading time: 12-15 minutes

Well, if the geological column holds no real evidence for or against macroevolution, where must we look next? We can look the same place Darwin did. After examining the geological column, Darwin looked at the details of the fossil record. The study of the fossil record is called paleontology (pay' lee un tah' luh jee), and it provides strong evidence against macroevolution.

Paleontology – The study of fossils

If macroevolution did occur, paleontologists should be able to find series of fossils that demonstrate how one species slowly evolved into another. If wild dogs, for example, did eventually give rise to horses, then there should be fossils of animals that are somewhere between a dog and a horse. Darwin called these life forms (which he assumed must have existed) intermediate varieties. Today, we call them intermediate links or transitional forms, because they represent a link (or transition) between one species and another. Unfortunately for Darwin, there were only a few examples of fossils that might be interpreted to be intermediate links, and even for those fossils, their status as intermediate links was quite questionable.

This lack of intermediate links was the most vexing problem that Darwin had with his hypothesis. In fact, in his book, he stated:
(block quote) Geological research, though it has added numerous species to existing and extinct genera, and has made the intervals between some few groups less wide than they otherwise would have been, yet has done scarcely anything in breaking the distinction between species, by connecting them together by numerous, fine, intermediate varieties; and this not having been affected, is probably the gravest and most obvious of all the many objections which can be raised against my views. (Charles Darwin, The Origin of Species, 6th ed, [New York, NY: Collier Books, 1962], 462) (block quote)

Notice what he says here. Darwin's hypothesis says that one species eventually led to another. Thus, there should be “fine, intermediate varieties” of fossils in between species. The fact that there weren't was a problem that he called “grave.” Additionally, note that he admits there are “many objections” which can be raised against his views. As we stated before, Darwin was very open about the flaws that he saw in his macroevolutionary hypothesis. In fact, he devoted many pages of his book to detailing the many objections which could be raised against his views!

Although Darwin could not find any good examples of intermediate links in the fossil record, he had a hope. He figured that geology and paleontology were still in their infant stages; therefore, they just hadn't found the intermediate links yet. He was convinced that as time went on, however, geologists and paleontologists would find them. Thus, he assumed that the intermediate links were currently just “missing” from the fossil record, but they would be found in time. Critics of macroevolution quickly coined the phrase “missing link” to emphasize that the fossil record was devoid of any evidence for macroevolution.

Well, what of these missing links? Has paleontology uncovered them? The answer to that is an unequivocal no. Read, for example, the words of Dr. David Raup, the curator of the Chicago Field Museum of Natural History and an expert on the fossil record.
(block quote) Well, we are now about 120 years after Darwin, and knowledge of the fossil record has been greatly expanded…ironically, we have even fewer examples of evolutionary transition than we had in Darwin's time. By this I mean that some of the classic cases of Darwinian change in the fossil record, such as the evolution of the horse in North America, have had to be discarded or modified as the result of more detailed information. (David Raup, Field Museum of Natural History Bulletin, 50:25, 1979 – emphasis added) (block quote)

So Dr. Raup says that the missing links are still missing. Darwin saw this fact as strong evidence against macroevolution, and Dr. Raup says that the situation is worse now than ever!

Since Dr. Raup's quote is more than 20 years old, you might wonder whether paleontology has discovered anything in the past two decades to make the situation any better for macroevolution. The answer is a clear and convincing no. Consider, for example, this summary of the state of paleontology in regard to macroevolution:

(block quote) …according to Darwin...the fossil record should be rife with examples of transitional forms leading from the less to more evolved...Instead of filling the gaps in the fossil record with so-called missing links, most paleontologists found themselves facing a situation in which there were only gaps in the fossil record, with no evidence of transformational intermediates between documented fossil species. (Jeffrey H. Schwartz, Sudden Origins, [New York, NY: John Wiley & Sons, 1999], 89) (block quote)

In other words, Dr. Schwartz (a macroevolutionist) is admitting that instead of finding transitional forms, paleontologists find mostly gaps. Now please understand that this flies in the face of what Darwin proposed. In fact, on the back cover of Dr. Schwartz's book, we read, “Darwin may have argued that new species emerge through a slow, gradual accumulation of tiny mutations, but the fossil record reveals a very different scenario – the sudden emergence of whole new species, with no apparent immediate ancestors.”

Now think about this for a minute. The hypothesis of macroevolution tries to explain something about earth's past. Since no one was around back then to tell us whether or not macroevolution actually happened, it is necessary to look for data that either support or contradict the hypothesis. Well, if you're looking for data about earth's history, where is the first place you would look? You would look in the fossil record! What does the fossil record say? It says that macroevolution never happened! Do you see what we mean when we say that scientists don't believe in macroevolution today because of the evidence? If the fossil record (the main place you look for information about earth's past) shows no evidence for macroevolution, scientists simply should not believe in it.

At this point, you might be thinking, “If the fossil record points so strongly against macroevolution, why do any scientists today believe in it?” Well, there are a couple of reasons. Some scientists are so committed to the idea of macroevolution that they have come up with special “variations” of macroevolution that attempt to “explain around” the fact that the fossil record does not support the idea. In fact, both Dr. Raup and Dr. Schwartz expose the lack of transitional forms in the fossil record specifically to promote one of these variations, which is called punctuated equilibrium. In this variation, it is assumed that the transitional forms that link one species to another do not live for very long. As a result, there is not much chance of them fossilizing. We will discuss this idea in more depth later in this module.

The second reason some scientists still cling to the hypothesis of macroevolution is that even though the fossil record has mostly gaps, there are some fossils that can be pointed to as possible transitional forms. Their status as transitional forms is highly questionable, but if you really need to believe in macroevolution, these fossils can give you at least some hope.

Consider, for example, the very famous fossil of a creature called Archaeopteryx (ar kee op' ter iks), which evolutionists want to believe is an intermediate link between reptiles and birds. This fossil is found in Jurassic rock, which (see Figure 9.2) contains remains of dinosaurs as well. In the geological column, Jurassic rock is underneath Cretaceous rock, which is underneath Tertiary rock. Although a few fossilized birds are found in other strata, the vast majority of bird fossils in the fossil record come from either Tertiary rock or the Quaternary rock that lies on top of it. Now remember, according to the assumptions of macroevolutionists, this would mean that birds did not really exist in significant numbers until the times during which Tertiary and Quaternary rock formed. Thus, during the times when Cretaceous and Jurassic rock were forming, macroevolutionists assume that birds had not yet evolved to any significant degree. Since Archaeopteryx is found in Jurassic rock, macroevolutionists conclude that it lived prior to most birds and that it could therefore be one of the transitional forms linking birds to their common ancestor, which is assumed to be some form of reptile.

In the vast majority of respects, this creature is a bird. The fossil shows very good imprints of feathers, and analysis of these feather imprints indicates that they are the kinds of feathers you see on birds that are living today. In fact, flightless birds that are living today have different feathers from those of birds that fly, and the fossil imprints indicate that Archaeopteryx had feathers of a flying bird.

In addition, the bones preserved in the fossil are very similar to the bones of birds that are living today. The skull, for example, shows that Archaeopteryx had a brain very similar to flying birds that are living today, and the fossilized inner ear indicates that Archaeopteryx had senses of hearing and balance that are comparable to flying birds that are living today. After performing X-ray scans of the skull and working with computer models, Dr. Timothy Rowe of the University of Texas at Austin said, “This animal had huge eyes and a huge vision region in its brain to go along with that and a great sense of balance. Its inner ear also looks very much like the ear of a modern bird.” (University of Texas at Austin Press Release, August 4, 2004, http://www.utexas.edu/cons/news/imaging.html, retrieved 01/06/05). In addition, paleontologists have been able to confirm bone structures that indicate Archaeopteryx had the same kind of lung design that birds living today have. In the end, then, Archaeopteryx seems to be a bird.

Why do many paleontologists consider Archaeopteryx a transitional form between reptile and bird? Because Archaeopteryx has teeth (which birds living today do not have), and it has claws on its wings, as shown on the illustration in the figure. No adult bird living today has claws on its wings. Some young birds (like the juvenile touraco or the juvenile hoatzin) have claws on their wings when they are young, but they lose them by the time they are adults. Some adult birds, like the ostrich, have structures on their wings that a few texts call “claws,” but they are better called “spurs,” because they do not have the actual structure of claws.

Because of these minor differences between Archaeopteryx and birds living today, macroevolutionists want to believe it is a transitional form between bird and reptile. After all, most (but not all) reptiles have teeth, and most (but not all) reptiles have front and back claws. Thus, the teeth in Archaeopteryx are supposed to represent reptilian teeth that had not quite “evolved away,” and the claws on its wings are supposed to represent front reptilian claws that had not quite blended in to the wing.

There are at least two problems with this interpretation. First, it assumes that birds living today are the only representations of proper birds. This is a rather myopic view of the natural world. We have many fossils that tell us a lot about the kinds of creatures that lived on this earth but are not living now. Are we to ignore them? If we do not ignore these creatures, we find that there were other birds that had teeth. In fact, there is a whole subclass devoted to such extinct birds, subclass Odontornithes (oh' don tor' nih theez). As a result, it is not clear that the teeth on Archaeopteryx are all that special.

The second problem with this interpretation is that it puts a lot of emphasis on rather minor structures in the animal. Based on its feathers, bone structure, lung structure, etc., Archaeopteryx seems to be a true bird. These are the main features we look at to determine whether or not something is a bird. To concentrate on two minor features, one of which exists in extinct birds, seems to be ignoring the vast majority of the data. Those who want to believe that Archaeopteryx is a transitional form will counter that we only see these structures in extinct birds, and therefore it is reasonable to assume that they were a part of the evolutionary process. However, species go extinct rather regularly, as demonstrated by the fossil record itself. The fact that all of the birds with these characteristics are now extinct is not surprising, since extinction is a major part of the fossil record.

Archaeopteryx at least illustrates how difficult it is for macroevolutionists to come up with transitional forms in the fossil record. If Archaeopteryx is a transitional form, it is a very late one. It must have been one of the very last creatures on the hypothetical macroevolutionary line between reptile and bird. Of all the transitional forms necessary to turn a reptile into a bird, it seems odd that the only one that has been found is so incredibly birdlike. Why isn't there a transitional form that is not so ambiguous?

As we said before, there are a few fossils like Archaeopteryx that macroevolutionists can present as transitional forms. The problem is, like Archaeopteryx, these supposed transitional forms are incredibly similar to one of the two types of creatures they are supposed to be linking. It seems much safer to conclude that these are just specialized versions of the creatures they are similar to, as opposed to transitional forms between two different kinds of creatures.

Another classic example of this kind of fossil is Australopithecus (aw stray' low pih' thih kus) afarensis (ah fuh' ren sis). This creature is supposed to be a transitional form between apes and humans. Although fossils of several creatures from genus Australopithecus have been discovered over the years, the best example is a partial skeleton of the A. afarensis species that has been nicknamed “Lucy.” This skeleton was discovered by Donald Johanson in 1974 near Hadar, Ethiopia. This was not the first discovery of fossils from this genus, and it was not the last. However, this skeleton is important because it is the most complete skeleton we have from this genus.

Although this might not look like a complete skeleton to you, it is actually quite a find. One of the problems with studying fossils is the fact that they tend to be very incomplete. As a result, scientists are left to speculate on the nature of a creature based often on far too little evidence. Many fossils were proclaimed intermediate links based on just a few tiny fragments of bone. Perhaps the greatest example was Nebraska Man. Scientists found a single tooth among the remains of some ancient tools. Based on that single tooth, scientists proclaimed that they had found one of the intermediate links between man and ape. They had artists draw full pictures of Nebraska Man, based only on a tooth! The pictures looked very convincing – a hulking, brutish figure that indeed looked like a link between man and ape. Later on, it was conclusively shown that the tooth actually belonged to a peccary, which is a certain type of pig! Thus, you should never believe the drawings that you see in books. Find out what fossils exist for the supposed creature. You will most likely be amazed at how few there are!

This specimen of Australopithecus afarensis, however, is quite a nice specimen, so we can learn a lot from it. When scientists examine such a specimen, they typically look at a few “key” bones that are characteristic of a certain kind of creature. For example, jaw bones are often very distinctive in most animals. Notice how the jaw bone of Australopithecus afarensis is shaped like a “V.” This is very distinctive of an ape. Also, the ratio between the size of the humerus and the size of the radius or ulna is also helpful in determining the kind of creature that Australopithecus afarensis was. Once again, the ratio of these bones indicates that Australopithecus afarensis is an ape. In fact, each bone in this entire skeleton indicates that Australopithecus afarensis is an ape.

If the bones indicate that it is an ape, why is Australopithecus afarensis considered an intermediate link? Well the hip joint and ankle joint can be constructed in such a way as to make Australopithecus afarensis stand upright in a relatively comfortable manner. This is unusual in apes. Most apes tend to be comfortable on all fours, whereas humans tend to be comfortable standing upright. Thus, because it is possible that Australopithecus afarensis might have stood upright, it is considered an intermediate link between man and ape.

There is a problem with this interpretation, however. Recent studies seem to indicate that Lucy most likely walked by using her knuckles. For example, Dr. Brian Richmond examined the wrist bones of two species in genus Australopithecus: A. afarensis and A. anamensis. They demonstrated that the wrists of these two species were quite similar to those of modern chimpanzees, which walk on both their hind legs and their knuckles. Thus, based on the wrist, you would classify Lucy as an ape that walks on its knuckles.

This is further supported by a study by Dr. Fred Spoor, who did CAT scans on the inner ears of members of genera Australopithecus and Paranthropus. Genus Paranthropus contains fossil creatures that are very similar to those in genus Australopithecus. In fact, some paleontologists think that these two genera should be combined, but that is still hotly debated. Spoor's study is important, as the inner ear is where balance is maintained, and if a creature walks upright, it needs a significantly different sense of balance from a creature that does not. What did Spoor find? His paper states, “…the semicircular canal dimensions in crania from southern Africa attributed to Australopithecus and Paranthropus resemble those of the extant great apes.” (Fred Spoor et al., “Implications of early hominid labyrinthine morphology for evolution of human bipedal locomotion,” Nature 369:645-8, 1994). The term “extant” just means “currently living.” Thus, Spoor's conclusion is that the inner ear of the members of genus Australopithecus is very similar to that of currently-living apes. This indicates that they probably did not walk upright, at least not habitually.

Once again, then, whether or not Australopithecus afarensis is an intermediate link depends on your point of view. If you want to believe in macroevolution, you can look at the possibility that it could stand upright and conclude that it is a transitional form. If you do not want to believe in macroevolution, you can look at the major features of the skeleton and the details of its wrists and inner ears and conclude that it is not.

The point, however, is quite clear. If macroevolution happened, the fossil record should be littered with intermediate links, as Darwin predicted. Instead, macroevolutionists can only present a few highly questionable ones. These supposed intermediate links closely resemble one of the two species they are supposed to link together. If intermediate links truly existed in the fossil record, you would think that at least one unambiguous intermediate link could be found somewhere!