Sabertooth

5. Extinctions

217 5 Extinctions The fact that no sabertooths have survived to the present day has often led to interpretations that see them as somewhat inferior, slow, or even maladaptive creatures that were left behind in the evolutionary race, replaced by the more fit “normal” big cats. The paleontological literature from the early part of the twentieth century abounds in negative judgments of the biological prowess of sabertooths, from those authors who doubted that the animals could hunt live prey at all to those who questioned even their ability to eat efficiently from carcasses. One almost suspects that the authors of some of this literature felt that the sabertooths “deserved” to become extinct. One good example is this quotation from a paper by the American paleontologist J. Hough: “It should be remembered , also, that by the middle Pleistocene the true cats were making their competition felt. Smilodon was too large for effective ambush in trees, too stupid for the type of jungle stalking characteristic of the lion or tiger, and too slow to run down its victims. These modes of attack were being developed rapidly among the true Felidae: Felis atrox, the lynx and the jaguar–remains of all of which are found at Rancho la Brea” (1950:135). After such a characterization of Smilodon, one wonders how it could manage to coexist with the feline cats of the American Pleistocene for hundreds of thousands of years. Why did it not go extinct sooner? Other scientists, while assuming that sabertooths were good enough at killing their prey, still thought that they were outcompeted by modern feline cats because the latter were faster and more agile (Simpson 1941). According to such views, sabertooths were adapted to hunt gigantic prey animals who were thick-skinned and slow, and when these behemoths disappeared at the end of the ice age, the only available prey were swift horses and antelope. In this new world, brute force and big teeth were not enough for a predator to survive, so sabertooths disappeared and feline cats triumphed. But, as we have already seen, although some sabertooth species were probably able to take prey animals that were larger and more ponderous than extant big cats can manage, other sabertooths preyed on relatively lightweight, agile prey, herbivores that are still not only extant but abundant. At any rate, even for the species that could on occasion take very large prey, medium-sized to large ungulates (including a wide range of ruminants and horses) would be the most abundant prey and would make up the bulk of the sabertooths’ diet, simply because they were the most available source of meat. Also, as we shall see below, “normal” big cats have by no means been immune to extinction, and not only are there several species of them that shared the fate of sabertooths, but some of the Early Interpretations of Sabertooth Extinctions Sabertooth 218 species that are still with us became confined to much smaller ranges, and some went to the brink of extinction at about the same time as the last sabertooths vanished. Another early explanation of the animals’ extinction saw the whole process of the evolution of sabertooth features as the cause of their demise. That theory, which was mentioned in passing in chapter 4, proposed that sabertooth evolution was part of an irreversible trend, so that with each generation, the sabers tended to grow slightly larger. As the effects of that trend accumulated, the animals supposedly became less and less able to feed, and extinction was thought to be the inevitable outcome. One interesting example of this view was the interpretation by E. D. Cope of what he called the “characters” of the skull of sabertooths: As nothing but the characters of the canine teeth distinguished these from the typical felines, it is to these that we must look for the cause of their failure to continue. Prof. Flower’s suggestion appears to be a good one, viz: that the length of these teeth became an inconvenience and a hindrance to their possessors. I think there can be no doubt that the huge canines in the Smilodons must have prevented the biting off of flesh from large pieces, so as to greatly interfere with feeding, and to keep the animals in poor condition. The size of the canines is such as to prevent their use as cutting instruments, excepting with the mouth closed, for the latter could not have been opened sufficiently to allow any object to enter it...