The amphibian-reptilian and reptilian-mammalian boundary is the one where the most frequent claims about transitional orders are made. Olson said: “The reptilian-mammalian transition has by far the best record that shows the origin of a new order.”1 Others claim that it has forms that perfectly fit the reptilian-mammalian boundary.
But, these are precisely the orders that are most similar, in skeletal outlines, to the parts that are preserved in the fossil record. The transition from invertebrates to vertebrates, fish to tetrapods with feet and legs, or one non-flying animal to a flying one, are a few examples that would require a revolutionary change in structure. Such transformations should enable easily recognizable transitional sequences in the fossil record if they truly occurred through the evolutionary process. On the other hand, if the creationist model is the correct model, precisely at those boundaries, the absence of transitional forms will be the most evident.
The opposite is true – both at the amphibian-reptilian and reptilian-mammalian boundaries, especially at the former. Although it is possible to distinguish living reptiles from amphibians based on basic skeletal characteristics, they are much more easily distinguished by soft parts, and in fact, the main characteristic that separates reptiles from amphibians is that reptiles have amniotic eggs, unlike amphibians, which do not possess them.
Many of the diagnostic characteristics of mammals, of course, lie in their soft anatomy or physiology. These include their mode of reproduction, warm-bloodedness, breathing method due to the presence of a diaphragm, suckling of offspring, and possession of hair.
Next, in order for the fossil record facts to align with the predictions of the evolutionary model, a true chronological sequence must be established that agrees with those predictions. This has not been possible with the amphibian-reptile model based on the fossil material discovered so far.
The known forms Seymouria and Diadectes, which are said to lie on the dividing line between amphibians and reptiles, come from the early Permian phase. This is at least 20 million years too late, according to the evolutionary timescale, for them to be ancestors of reptiles. The so-called “primitive” reptiles from the order Cotylosauria were found not in the Permian period or later, but in the previous Upper Carboniferous period.
In fact, the “mammal-like” reptiles of the subclass Synapsida, which are assumed to have led to mammals, were found in the Upper Carboniferous, possibly even in the early Upper Carboniferous period. Thus, Seymouria and Diadectes, “ancestors” of reptiles, would not only be dated several tens of millions of years after reptiles but would also be dated even after the “ancestors” of mammals for an equally long period of time.
The creatures included in the class Mammalia represent a diverse group. All are warm-blooded and females have mammary glands to feed their offspring. Mammals cover 32 orders, most of which are placental mammals, but they also include Monotremata, which includes the spiny anteater that lays eggs and the Platypus, which also lays eggs, and Marsupialia, which includes opossums and marsupial pouch-bearers, such as kangaroos and wallabies.
It is interesting to note that there are claims about discovered transitional forms between reptiles and mammals, while some evolutionists admit that transitional ancestors have not been found for any of the 32 mammal orders. Thus, George Gaylord Simpson, after the claim that there is no trace of fossils anywhere in the world that will narrow the gap between Hyracotherium (“Eohippus”), which evolutionists assume to have been the first horse, and its supposed ancestral order Condylarthra, further says:
“This applies to all 32 orders of mammals… The earliest and most primitive known members of each order already have the basic ordinal characteristics, and in no case is there known to be an approximately continuous series from one order to another. In most cases, the break is so sharp and the gap so large that the origin of the order is speculative and very controversial.”
- Literature
- E. C. Olson, The Evolution of Life, The New American Library, New York, 1965, p. 207.
- G. G. Simpson, Tempo and Mode in Evolution, Columbia University Press, New York, 1944, p. 105.