Deutsch Ashley R, Berger Arin, Martens Lara L, Witt Benjamin R, Smith Rachel L J, Hartstone-Rose Adam
Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina, USA.
Anat Rec (Hoboken). 2024 Jun 28. doi: 10.1002/ar.25529.
Masticatory gape and bite force are important behavioral and ecological variables. While much has been written about the highly derived masticatory anatomy of Smilodon fatalis, there remains a great deal of debate about their masticatory behaviors. To that end, we establish osteological proxies for masticatory adductor fascicle length (FL) based on extant felids and apply these along with previously validated techniques to S. fatalis to provide estimates of fascicle lengths, maximum osteological gapes, and bite force. While the best correlated FL proxies in extant felids do not predict particularly long fascicles, these proxies may be of value for less morphologically distinct felids. A slightly less well correlated proxy predicts a temporalis FL 15% longer than that of Panthera tigris. While angular maximum bony gape is significantly larger in S. fatalis than it is in extant felids, linear gape at the canine tip and carnassial notch were not significantly different from those of extant felids. Finally, we produce anatomical bite force estimates of 1283.74 N at the canine and 4671.41 N at the carnassial, which are similar in magnitude to estimates not of the largest felids but of the much smaller P. onca, with S. fatalis producing slightly less force at the canines and more at the carnassials. These estimates align with previous predictions that S. fatalis may have killed large prey with canine shearing bites produced, in part, by force contributions of the postcranial muscles.
咀嚼张口度和咬合力是重要的行为和生态变量。虽然关于致命剑齿虎高度特化的咀嚼解剖结构已有大量著述，但关于它们的咀嚼行为仍存在诸多争议。为此，我们基于现存猫科动物建立了咀嚼内收肌束长度（FL）的骨学代理指标，并将这些指标与先前经过验证的技术一起应用于致命剑齿虎，以估算肌束长度、最大骨学张口度和咬合力。虽然现存猫科动物中相关性最佳的FL代理指标并不能预测出特别长的肌束，但这些指标可能对形态差异较小的猫科动物具有价值。一个相关性稍弱的代理指标预测颞肌FL比孟加拉虎长15%。虽然致命剑齿虎的角向最大骨张口度显著大于现存猫科动物，但其犬齿尖端和裂齿凹口处的线性张口度与现存猫科动物并无显著差异。最后，我们得出犬齿处的解剖学咬合力估计值为1283.74牛，裂齿处为4671.41牛，其数值与不是最大的猫科动物而是小得多的美洲豹的估计值相似，致命剑齿虎在犬齿处产生的力量略小，在裂齿处产生的力量更大。这些估计结果与先前的预测一致，即致命剑齿虎可能通过部分由颅后肌肉贡献力量产生的犬齿剪切咬合力捕杀大型猎物。
