Pleistocene Mammals in the Midwest
Sabertoothed cat, Smilodon fatalis
Sabertoothed cats are some of the most well-known and fascinating animals from the recent Ice Age. Smilodon fatalis, a dirk-toothed cat, was one of two species of late Pleistocene cats with enlarged upper canines, and they are the animal that most people associate with the name "sabertooth cat". You can read more about the other late Pleistocene species, Homotherium serum, here.
Carnivora (Dogs, Cats, Bears, etc.)
Smilodon fatalis was about as long as the modern African lion, but unlike lions, it had short, powerful legs, a short tail, and a heavy muscular build. Whereas modern cats are typically built for speed and agility, Smilodon was built for strength and power. In fact, comparison of skeletal measurements indicates that Smilodon's body was built more like a bear than a modern cat (Wroe et al. 2008), although with more flexibility and agility than is seen in bears. Smilodon's most dramatic and well-known feature is its enlarged upper canines, which were roughly 18-25 cm (7-10 inches). As in other dirk-toothed cats, these upper canines were long and narrow, and they were flat in cross-section, rather than round like those of modern cats (Martin 1980). In order to accommodate the length of the canines, or sabers, Smilodon had a narrow lower jaw that allowed the canines to protrude beneath its chin when its jaw was closed.
Based on the shape of their teeth and the lack of any rounded surfaces (e.g., flat molars), there is no question that S. fatalis was a hypercarnivore who preyed on live animals (Wroe et al. 2008). However, the high rate of tooth breakage recorded for this animal at the Rancho La Brea tar pits indicates that the animals recovered from that site also consumed a fair amount of bone, possibly due to high competition with other carnivores and the need to consume kills quickly (Van Valkenburgh and Hertel 1993). The robusticity of their bodies combined with powerful forelimbs suggests that they specialized in preying on large species (Wroe et al. 2008), and a recent bone chemistry study suggests that they may have preyed preferentially on animals such as bison or camels (Coltrain et al. 2004). Because these cats would have been more powerful than agile, they likely hunted large prey from ambush - that is, stalking and attacking prey animals from a hiding place.
During hunting, the sabers were probably used to stab prey animals in the neck or belly, causing them to bleed to death. They may also have been used as weapons to fight other carnivores, as indicated by sabertooth-sized holes and healed lesions found on Smilodon bones and skulls and the recovery of a dire wolf skull penetrated by a broken Smilodon saber. In fact, the documentation of numerous Smilodon bones with healed injuries and/or degenerative diseases, many of which would have been debilitating to the animal, suggests that these cats were social animals who lived in packs. Without assistance from other cats, at least in the form of food, the injuried animals would have died before their bones could start to heal.
North American Ice Age Distribution:
Smilodon remains have been recovered from Pleistocene sites in North and South America and Eurasia, although they seem to have disappeared from Eurasia by the middle Pleistocene. They persisted in North America up to the end of the Pleistocene (ca. 11,500 years ago), and they have been recovered in great numbers from numerous sites in the western and southern U.S. The best documented collection of Smilodon remains includes thousands of individuals recovered from the Rancho La Brea tar pits in southern California.
Status at the end of the Pleistocene:
It is thought that loss of habitat and the disappearance of important prey animals, such as mammoths and mastodonts, at the end of the Pleistocene contributed heavily to their extinction.
Midwestern Paleontological Finds:
Like many apex carnivores, localities containing Smilodon are rare in the Midwest. Notable occurences include, Harrodsburg Fissure in Monroe County, Indiana, Crevice Cave in Perry County, Missouri, and Hurricane River Cave, Searcy County, Arkansas. The latter locality is the only one of the three that is likely Wisconsin in age (Hawksley et al. 1980).
- The development of elongated, flattened canine teeth, like those of Smilodon, is common in the evolution of large carnivorous mammals. Over the last 45 million years this type of tooth evolved separately in at least two lineages of cats, two lineages of nimravids (an extinct family allied to the cats, hyaenas, and civets), and one lineage of marsupial (in South America).
Coltrain, J. B., J. M. Harris, T. E. Cerling, J. R. Ehleringer, M. Dearing, J. Ward, and J. Allen. 2004. Trophic level relationships among Rancho La Brea fauna and their implications for the paleoecology of the late Pleistocene based on bone collagen stable carbon and nitrogen isotope chemistry. Palaeogeography, Palaeoclimatology, Palaeoecology 205:199–219.
Hawksley, O., Youngsteadt, N. W., & Youngsteadt, J. O. 1980. A sabertooth cat, Smilodon floridanus from northwest Arkansas. NSS Bulletin, 42, 8-14.
Martin, L. D. 1980. Functional Morphology and the Evolution of Cats. Transactions of the Nebraska Academy of Sciences 9: 141-154.
Van Valkenburgh, B., and Hertel, F. 1993. Tough times at La Brea: tooth breakage in large carnivores of the late Pleistocene. Science 261:456–459
Wroe, S., Lowry, M., and Anton, M. 2008. How to build a mammalian super-predator. Zoology 111: 196–203