Lees John, Garner Terence, Cooper Glen, Nudds Robert
Faculty of Life Sciences , University of Manchester , Manchester M13 9PT , UK.
School of Mechanical, Aerospace and Civil Engineering , University of Manchester , Manchester M13 9PL , UK.
R Soc Open Sci. 2017 Feb 15;4(2):160927. doi: 10.1098/rsos.160927. eCollection 2017 Feb.
It was previously suggested that the flight ability of feathered fossils could be hypothesized from the diameter of their feather rachises. Central to the idea is the unvalidated assumption that the strength of a primary flight feather (i.e. its material and structural properties) may be consistently calculated from the external diameter of the feather rachis, which is the only dimension that is likely to relate to structural properties available from fossils. Here, using three-point bending tests, the relationship between feather structural properties (maximum bending moment, and Young's modulus, ) and external morphological parameters (primary feather rachis length, diameter and second moment of area at the calamus) in 180 primary feathers from four species of bird of differing flight style was investigated. Intraspecifically, both and were strongly correlated with morphology, decreasing and increasing, respectively, with all three morphological measures. Without accounting for species, however, external morphology was a poor predictor of rachis structural properties, meaning that precise determination of aerial performance in extinct, feathered species from external rachis dimensions alone is not possible. Even if it were possible to calculate the second moment of area of the rachis, our data suggest that feather strength could still not be reliably estimated.
此前有人提出，可以根据有羽毛化石的羽轴直径来推测其飞行能力。这一观点的核心是一个未经证实的假设，即主飞羽的强度（即其材料和结构特性）可以通过羽轴的外径一致地计算出来，而羽轴外径是唯一可能与化石中可得的结构特性相关的维度。在此，通过三点弯曲试验，研究了来自四种飞行方式不同的鸟类的180根主飞羽的羽毛结构特性（最大弯矩和杨氏模量）与外部形态参数（主羽轴长度、直径和羽根处的截面惯性矩）之间的关系。在种内，最大弯矩和杨氏模量均与形态密切相关，分别随所有三种形态测量值的减小和增大而变化。然而，在不考虑物种的情况下，外部形态对羽轴结构特性的预测能力很差，这意味着仅根据外部羽轴尺寸精确确定已灭绝有羽毛物种的空中飞行能力是不可能的。即使能够计算出羽轴的截面惯性矩，我们的数据表明羽毛强度仍然无法可靠地估计。
