What makes a fang? phylogenetic and ecological controls on tooth evolution in rear-fanged snakes

Background: Fangs are a putative key innovation that revolutionized prey capture and feeding in snakes, and – along with their associated venom phenotypes – have made snakes perhaps the most medically-significant vertebrate animals. Several snake clades are known for their forward-positioned fangs, and these clades (Elapidae; Viperidae) contain the majority of snakes that are traditionally considered venomous. However, many other snakes are \"rear-fanged\": they possess potentially venom-delivering teeth situated at the rear end of the upper jaw. Quantification of fang phenotypes – and especially those of rear-fanged species – has proved challenging or impossible owing to the small size and relative rarity of many such snakes. Consequently, it has been difficult to understand the evolutionary history of both venom and prey-capture strategies across extant snakes. We quantified variation in the dentition of 145 colubriform (“advanced”) snake species using microCT scanning and compared dent...

研究背景：毒牙被视为一项关键性演化创新，彻底革新了蛇类的猎物捕获与进食行为，再加上与之关联的毒液表型，使得蛇类或许成为了对人类医学意义最为重大的脊椎动物类群。多个蛇类演化支以拥有前位毒牙而著称，这两类演化支（眼镜蛇科Elapidae、蝰科Viperidae）包含了传统认知中绝大多数被视为有毒的蛇类。然而，另有大量蛇类属于“后位毒牙类群”：它们在上颌后端生有具备毒液输送潜力的牙齿。由于多数此类蛇类体型小巧且相对稀有，对其毒牙表型（尤其是后位毒牙类群的表型）进行量化分析长期以来被证明极具挑战性，甚至无法实现。因此，厘清现生蛇类的毒液演化历史与猎物捕获策略的演化历程始终存在诸多障碍。本研究通过显微计算机断层扫描（microCT）对145种游蛇形（“高等”）蛇类的齿列变异进行了量化分析，并对其齿部……