“Dawn Horse” Is a Good “Ancestor” For Rhinos
Discredits Horse Evolution?

In my previous essay I debunked the creationist claim that Hyracotherium (also called Eohippus or “dawn horse”) is really a type of hyrax, a group of animals living today in Africa and Asia. Now we deal with another dubious creationist claim about this fossil genus.

Duane T. Gish tells us in Impact #87 “The Origin of Mammals” the following:

Others also doubt whether Hyracotherium was related to the horse. For example, Kerkut states, “In the first place it is not clear that Hyracotherium was the ancestral horse. Thus Simpson (1945) states, ‘Matthew has shown and insisted that Hyracotherium (including Eohippus) is so primitive that it is not much more definitely equid than tap i rid [sic], rhinocerotid, etc., but it is customary to place it at the root of the equid group.’”¹⁸ In other words, Hyracotherium is not any more like a horse than it is similar to a tapir or a rhinoceros, and thus just as justifiably it could have been chosen as the ancestral rhinoceros or tapir. It seems, then, that the objectivity of those involved in the construction of the phylogenetic tree of the horse was questionable from the very start, and that the “horse” on which the entire family tree of the horse rests was not a horse at all.

¹⁸ Kerkut, G. A., Implications of Evolution, New York: Pergamon Press, 1960, p. 149.

This is another case of creationist quotation mining and, as usual, it is out-of-context. The scientist who is being quoted out of context this time is George Gaylord Simpson. Let's investigate what Simpson really thought on this matter. Simpson¹ wrote:

For instance, Matthew (1926) pointed out, but latter students mostly ignored, the fact that eohippus [Hyracotherium] was not a horse, that it is about as good an ancestor for Rhinoceros as for Equus [genus with modern horses and zebras]. In effect, there was no family Equidae [Horse family] when eohippus lived. The family and all its distinctive characters developed gradually as time went on. Eohippus is referred to the Equidae because we happen to have more complete lines back to it from later members of this family than from other families. There is no particular time at which the Equidae became a family rather than a genus or a species; the whole process is gradual and we assign the categorical rank after the result is before us.

As Futuyma² after quoting the above to dispute Gish’s claim noted:

The point, of course, is that Hyracotherium and its relatives were the ancestors of both horses and rhinoceroses, and can’t be assigned to either of these groups.

Indeed, Simpson³ wrote in another book:

Matthew has pointed out (e.g., 1926) that Hyracotherium (Eohippus) is so nearly a generalized primitive perissodactyl [the order of mammals that includes horses, rhinos, tapirs, etc.] that it could be near the ancestry, if not itself the ancestor, of all the later families of perissodactyls. Knowledge of a nearly continuous sequence leading to the horses and ignorance of smaller or larger parts of sequences leading to other families (tapirs, rhinoceroses, titanotheres, and so forth), at first closely similar, might be due only to chance….

Thus, according to Simpson, not only is “Dawn Horse” a possible ancestor of horses and a possible ancestor of rhinos, but the reason we call it “horse” is that we have a better fossil record for the horse lineages. We can conclude that Gish has misrepresented the views of Simpson and indeed has misrepresented evolution. I will also point out that Simpson’s paragraph goes on to mention a gap between Hyracotherium and its most likely ancestors. Gish mentions this sentence and then quotes the next paragraph. (This is in the Gish’s paragraph which cites the third footnote, the first paragraph of Gish’s essay the mentions Simpson.) Thus I think it is clear Gish has either conveniently ignoring content that does not help his thesis or has uncritically cribbed a previous creationist.

In the previous quotes, including the one Gish quoted, Simpson referred to W. D. Matthew’s⁴ 1926 article “The Evolution of the Horse: A Record and Its Interpretation.” Matthew said on page 153:

It is quite possible that certain species of Eohippus, when more intensively studied, will appear to be more directly in the line of ancestry of the horse, others of the tapir or rhinoceros or of some of the extinct phyla of Perissodactyls…

Thus leading paleontologists have been clear on this issue for the better part of a century and we have even more evidence that Gish has failed to accurately describe what paleontologists have found.

Moving to much more recent sources (written after Gish’s essay), Part 2B of the “Transitional Vertebrate Fossils FAQ” tells us:

Note that Hyrac[otherium] differed from other early perissodactyls (such as tapir/rhino ancestors) only by small changes in tooth cusps and in body size.

Dr. Keith B. Miller tells us in his “Taxonomy, Transitional Forms, and the Fossil Record” the following:

The significance of the fossil record of horses becomes clearer when it is compared with that of the other members of the order Perissodactyla (“odd-toed ungulates”). The fossil record of the extinct titanotheres is quite good (Fig. 7), and the earliest representatives of this group are very similar to “Eohippus” (Stanley, 1974; Mader, 1989). Likewise, the earliest members of the tapirs and rhinos were very “Eohippus”-like. Thus, the different perissodactyl groups can be traced back to a group of very similar small generalized ungulates (Radinsky, 1979; Prothero, et al., 1989; Prothero & Schoch, 1989) (Fig. 8). But this is not all; the most primitive ungulates (hoofed mammals) are the condylarths, which are assemblages of forms transitional in character between the insectivores and true ungulates (Fig. 9). Some genera and families of the condylarths had been previously assigned to the Insectivora, Carnivora, and even Primates (Romer, 1966). Thus, the farther you go back in the fossil record, the more difficult it is to place species in their “correct” higher taxonomic group. The boundaries of taxa become blurred.

Simpson⁵ wrote that “the orders all converge backwards in time to different degrees” in the same paragraph which Gish quoted (the same paragraph with his footnote 3). Of course, that taxa converge as one goes back in time is very unsurprising if one accepts evolution.

Gish is also taking advantage of a common misconception of evolution held by the public at large. Most people think of evolution as a “ladder” of progress. Gish certainly knows that modern evolutionary biologists think of evolution consists of many lineages splitting and thus the “ladder” is really a “bush.” And yet his argument which I debunked in this article is really nothing more than the false assumption that evolution forms a “ladder.”

Also see my “George Gaylord Simpson said there are no transitional fossils?” for other examples of Simpson being unethically quoted by creationists.

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