Data from: Has snake fang evolution lost its bite? New insights from a structural mechanics viewpoint

Venomous snakes—the pinnacle of snake evolution—are characterized by their possession of venom-conducting fangs ranging from grooved phenotypes characterizing multiple lineages of rear-fanged taxa to tubular phenotypes present in elapids, viperids and atractaspidines. Despite extensive research, controversy still exists on the selective pressures involved in fang phenotype diversification. Here, we test the hypothesis that larger fangs and consequently a shift to an anterior position in the maxilla evolved to compensate for the costs of structural changes, i.e. higher stress upon impact in tubular fangs compared to grooved fangs. Direct voxel-based stress simulations conducted on high-resolution µCT scans, analysed within a phylogenetic framework, showed no differences in stress distribution between the three fang phenotypes, despite differences in (relative) fang length. These findings suggest that additional compensatory mechanisms are responsible for the biomechanical optimization and that fang length might instead be related to differential striking behaviour strategies.

毒蛇——蛇类演化的巅峰类群——以具备排毒毒牙为典型特征，其毒牙形态涵盖多支后毒牙类群所具有的沟槽型（grooved phenotypes），以及眼镜蛇科（Elapidae）、蝰科（Viperidae）与穴蝰亚科（Atractaspidines）所拥有的管状型（tubular phenotypes）。尽管已有广泛深入的研究，但关于驱动毒牙形态多样化的选择压力，学界仍存在争议。本研究针对“更长的毒牙以及随之而来的上颌骨前位演化，是为了补偿结构变化带来的代价——即相较于沟槽型毒牙，管状型毒牙在咬合时承受更高应力”这一假说展开验证。我们基于高分辨率微计算机断层扫描（µCT）扫描结果开展直接体素应力模拟，并结合系统发育框架进行分析，结果显示：尽管三类毒牙的（相对）毒牙长度存在差异，但其应力分布并无显著不同。上述研究结果表明，存在其他补偿机制促成了生物力学优化，而毒牙长度或许反而与差异化的攻击行为策略相关。