Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania, USA.
J Morphol. 2024 Aug;285(8):e21758. doi: 10.1002/jmor.21758.
Anatomy compromises the precision and accuracy of measurements made of the body length and head size of live snakes. Body measures (snout-vent length, SVL) incorporate many synovial intervertebral joints, each allowing flexion and limited extension and compression. Radiographs of the trunk in 14 phylogenetically diverse species in resting and stretched conditions combined with dissections and histological analysis of intervertebral joints show that the synovial nature of these joints underlies the variance in SVL measures. Similarly, the ubiquity and variety of viscoelastic tissues connecting mobile snout and jaw elements of alethinophidian snakes underlie variances in length and width measures of the head. For the overall size of the head and jaw apparatus, the part that can be most easily and relatively precisely measured for many snakes is the mandible because it has only one mobile joint. As to accuracy, the anatomy of intervertebral and cranial joints supports the hypothesis that in living snakes, the head and trunk have no exact size.
解剖学影响了活体蛇的体长和头长测量的精度和准确性。体尺（吻肛长，SVL）包含许多滑膜椎间关节，每个关节都允许弯曲和有限的伸展和压缩。对 14 种不同亲缘关系的物种在休息和伸展状态下的躯干进行 X 光检查，并结合对椎间关节的解剖和组织学分析表明，这些关节的滑膜特性是 SVL 测量值差异的基础。同样，连接具有活动的吻部和颚部的 Alethinophidia 蛇的粘弹性组织的普遍性和多样性是头部长度和宽度测量值差异的基础。对于头部和颚部装置的整体大小，对于许多蛇来说，最容易和相对精确测量的部分是下颌骨，因为它只有一个活动关节。至于准确性，椎间关节和颅关节的解剖结构支持这样的假设，即在活体蛇中，头部和躯干没有确切的大小。
