Answers in Genesis in a file titled “There are no transitional fossils” which is part of an article by Jonathan D. Sarfati attacking an essay published in the Washington Post tells us:
The ‘mammal-like reptiles’ are commonly asserted to be transitional. But according to a specialist on these creatures:
‘each species of mammal-like reptile that has been found appears suddenly in the fossil record and is not preceded by the species that is directly ancestral to it. It disappears some time later, without leaving a directly descended species …’
Tom Kemp, ‘The Reptiles that Became Mammals’, New Scientist 92 [sic, it is really 93]:583, 4 March 1982
This is yet another example of creationists dishonestly taking a little snippet of a work in order to suggest an author is saying something he is not. I went to the library and found Dr. Kemp’s article. This is another case of a scientist referring to species level transitions and the creationists saying the scientist is referring to the transitions between larger groups. (See: “Stephen Jay Gould Says There Are No Transitional Fossils?”)
Lets first check the direct context of what Dr. Kemp said. I will quote his Rule 6 and then the full paragraph where the above Kemp quote came from (what Sarfati quoted is in green):
Rule 6: Within each lineage, species keep going extinct abruptly, only to be replaced by new, similar species. This is the phenomenon of species turnover.…
Rates of speciation and extinction. Rule 6 encapsulates one of the most important observations from the fossil record—species turnover. Each species of mammal-like reptile that has been found appears suddenly in the fossil record and is not preceded by the species that is directly ancestral to it. It disappears some time later, without leaving a directly descended species, although we usually find that it has been replaced by some new, related species. The concept of punctuated equilibria—which envisages evolutionary change occurring in a series of jumps, with relatively little change in between—was introduced in 1972 by Niles Eldredge and Stephen Jay Gould, and accounts for this rather well.
Kemp was not in any way denying that the mammal-like reptiles are intermediate between reptiles and mammals. What he is saying is that it is very rare to find an transition between one species and an another immediately related species because new species usually form from small geographically isolated populations and the process is often rather fast (fast to a geologist).
Lets look at more of the Kemp’s article and see that it documents what Sarfati implies it does not: that the mammal-like reptiles are indeed transitional in the larger sense.
Evolution has often had what is termed an “adaptive radiation.” What this is when an evolutionary line rapidly evolve into many lines that have usually diversified a great deal. An example of this was when the dinosaurs and other creatures died off at the end of the Cretaceous period they left a void which was filled when various then minor mammalian lines diversified into many lines filling ecological niches ones held by extinct lines.
Kemp tells us that there where three distinct phases of adaptive radiation in the evolution of the mammal-like reptiles. The first adaptive radiation consists of the Pelycosaurs.
Archaeothyris, an early pelycosaur, was a lizard-like animal about 50 cm long that differed little from the primitive reptiles alive at the same time; the major distinction is a small space—the temporal fenestra—in the cheek region of the skull. This little space is important because it permits the muscles of the jaw itself to become more efficient. Indeed, the temporal fenestra is a hallmark of all mammal-like reptiles which persists right through to the mammals; so all the synapsids [mammals and mammal-like reptiles] must have evolved from an ancestral form not unlike Archaeothyris.
Kent points out that the Pelycosaurs diversified into multiple groups including carnivores, fish-eaters, and herbivores.
Then the Pelycosaurs suffered a mass extinction at which time the first therapsids appeared and underwent an adaptive radiation. The therapsids were more mammal-like in that they had larger temporal fenestrae and had a more mammal-like mode of locomotion.
In the late Permian Period a group of therapsids, the cynodonts, appeared. They “form the next link in the synapsid chain.” Another mass extinction occurred at the end of the Permian and the cynodonts were one of the few surviving groups.
Cynodonts were even more like mammals than were the previous therapsids. They carried on the theme of jaw improvements, developing complex multi-cusped teeth and more powerful musculature. From the Early Triassic stock of cynodonts arose the third phase of adaptive radiation of the mammal-like reptiles. Again, the basic stock diverged into a variety of types; large and small herbivores and carnivores, and as the Triassic went on the fossils come to look increasingly mammalian. But the cynodonts too became extinct at the close of the Triassic, leaving only their tiny descendants—true mammals—to persist into the Jurassic and beyond.
So what Kemp is really telling us is that the mammal-like reptiles over time started very similar to then contemporary reptiles and over time became more and more like mammals. Indeed Kemp summarized it as his rule 4:
Rule 4: All members of the new radiation are more advanced (that is, more mammal-like) than any members of the previous radiation.
Does this sound like denying that mammal-like reptiles are intermediate, i.e. a transitional, between mammals and reptiles to you? Lets let Kemp elaborate on this:
The third rule that addresses the direction of morphological change is Rule 4, the progress toward mammalian structure. We can chart the acquisition of mammalian characters by studying those particular fossils that lie closest to the hypothetical lineage from primitive pelycosaurs to mammals. Each biological system that shows up in the skeleton—primarily feeding and locomotion but also such things as hearing, respiration, and brain size—evolved step by step towards the mammalian condition. Since all the systems did this, there is an apparent correlation among them, although this correlation is not absolute because we do sometimes see that one system becomes more mammal-like without the other systems accompanying it. Such a pattern of evolution of characters is called a correlated progression, and it comes about because all the structures and functions of an organism are integrated within the whole. They must, perforce, change together if the animal is to continue to work properly.
The mammal-like reptiles fossils show a “step by step” evolution towards mammals. So how can Sarfati use this article to support his thesis that there are no transitional forms? By quoting a small part of what the Dr. Kemp said, removing it from its context, and giving a false impression of what the context was.
Now the article has a note that it was based on part of book by same author. That book is Mammal-like Reptiles and the Origin of Mammals (London: Academic Press, 1982). I looked at that book in a library. I looked briefly at a few of its chapters and found some stuff that supports my thesis that Kemp really does think that they really are transitions from reptiles to mammals. One page 1:
Due to a series of fortunate geological coincidences the fossil record of the mammal-like reptiles is more complete than that of any other group of terrestrial vertebrates, with the exception of the Tertiary mammals. Moreover, their evolution spanned a huge morphological progression, from early forms of a very primitive reptilian grade through to others which are technically to be regarded as mammals. Therefore this is the one example known where evolution of one class of vertebrates from one class to another class is well documented by the fossil record….
And Sarfati wants us to think that Kemp does not accept the mammal-like reptiles as being transitional?
Indeed the mammal-like reptiles and mammals grade into each other to such a degree that it is hard to make a clear line from where one starts and the other begins. On page 294, Kemp has part of his documentation of this in this paragraph:
The traditional definition of the mammals has been based upon the structure of the jaw articulation. Mammals have lost the reptilian articular-quadrate hinge and gained the new dentary-squamosal hinge…However, the array of forms now known to have possessed both hinges simultaneously has rather reduced the clarity of this character. If the gain of the dentary-squamosal hinge is used, then both the therian and the non-therian mammals would be included, but also the tritheledontids and possibly tritylodontids and Probainognathus. If one the other hand, the loss of the articular-quadrate hinge is used, Mammalia would be restricted to the modern therians, the monetremes, and probably the multituberculates, while the obvious relatives of these groups in the Mesozoic, such as Kuehneotherium and the morganucodontids, would be excluded.
Kemp then mentioned problems with another definition of what is a mammal. He concludes on page 295:
There is a necessarily a subjective decision to be made about which groups should be included as mammals….
If there were no transitional forms between the mammals and the reptiles than it would not be subjective as to what should and should not be called a “mammal.”
Lets look the context of what Sarfati was saying. Sarfati’s quotation of Dr. Kemp was to dispute what Boyce Rensberger, a reporter for the Washington Post, had written. The segment of Sarfati’s article which I reproduced at the top of this page, was Sarfati’s response to this:
There are, for example, excellent skeletons of extinct animals showing the transitions…from reptile to mammal (it happened about the time the first dinosaurs were arising),… [I deleted numerous other things which Rensberger correctly states there are transitions for.]
If Kemp’s views are the best that Sarfati can do to dispute what Rensberger wrote, then we can say with confidence after looking what Kemp really wrote, that Rensberger is right and Sarfati is wrong. And not only is Sarfati wrong, but he was simply not honest in this matter.
Also see my “George Gaylord Simpson Said There Are No Transitional Fossils?” which had details on another quote which Sarfati used to dispute Rensberger.