Paleontologist Jack Tseng, along with colleagues, theorized that the double fangs found in some saber-toothed cat skulls served the purpose of stabilizing the permanent saber tooth against breakage during eruption. This theory was based on growth data indicating that the baby tooth was present alongside the permanent tooth for up to 30 months. In a new study published in The Anatomical Record, Tseng provides evidence that having a baby tooth next to the saber tooth made it more stable against lateral breakage. Computer modeling and testing of plastic saber tooth replicas supported this hypothesis, suggesting that the presence of the baby tooth acted as a mechanical buttress during the adolescent stage of the saber-toothed cat.
Tseng speculates that the extended presence of the baby canine alongside the permanent saber tooth may have provided a form of insurance or protection for the saber as the animals learned how to hunt without damaging them. Once the baby tooth fell out, the adult would be left with just the saber, having presumably learned to be careful with it during the adolescent stage. This unusual feature of the double fang stage potentially allowed the young saber-toothed cats to experiment, take risks, and learn how to become fully fledged predators without endangering their sabers. The study offers new insights into the growth and hunting behaviors of saber-toothed cats through a mechanical lens.
Using beam theory, a type of engineering analysis, Tseng modeled the saber teeth to understand how they could withstand lateral forces without breaking. By combining this analysis with finite element modeling, he found that the stiffness of the saber tooth decreased with increasing length, making it more susceptible to breakage. However, when a supportive baby tooth was added to the model, the stiffness of the saber tooth increased, reducing the risk of breakage. This finding suggests that the presence of the baby tooth alongside the saber tooth helped maintain its stability during the growth process.
The study has implications for understanding how saber-toothed cats and other saber-toothed animals hunted as adults. Despite having thin-bladed knives for canines, adult saber-toothed cats managed to avoid frequent breakage of their teeth, even during biting forces. The presence of the baby tooth alongside the saber tooth may have provided a protective mechanism during the growth process, allowing the animals to develop their predatory skills without damaging their sabers. This evolutionary adaptation likely played a crucial role in the hunting strategies of saber-toothed animals.
Tseng also suggests that a similar stabilization mechanism may have evolved in other saber-toothed animals, although no examples of double fangs have been found in other species. Some skulls have been discovered with adult teeth elsewhere in the jaws but milk teeth where the saber would erupt, indicating a prolonged retention of the baby canines. This suggests that the stabilization system observed in Smilodon fatalis may have been a common feature among saber-toothed animals. Further research using 3D-printed replicas of saber teeth aims to refine the understanding of how the presence of the baby tooth influenced the strength and stability of saber teeth in different species.
Overall, the study sheds light on the unique adaptation of Smilodon fatalis and other saber-toothed animals to protect their saber teeth during growth and hunting. The presence of the baby tooth alongside the saber tooth appears to have served as a mechanical support system, reducing the risk of breakage and allowing the animals to develop their predatory skills without damaging their most vital weapons. The research highlights the importance of understanding the biomechanical aspects of tooth structure in prehistoric animals to gain insights into their behavior and evolution.
