Garland Kathleen L S, Hay Eleanor M, Field Daniel J, Evans Alistair R
School of Biological Sciences, Monash University, Melbourne, VIC, Australia.
Department of Biology, University of Miami, Coral Gables, FL 33146, USA.
iScience. 2025 Mar 19;28(4):112246. doi: 10.1016/j.isci.2025.112246. eCollection 2025 Apr 18.
Vertebrate beaks show a remarkable diversity of forms, epitomized by birds and non-avian theropods. Few studies have investigated how underlying developmental processes influence beak shape. The power cascade is a model of growth describing the log-log linear relationship of the beak radius with distance from the tip. We measured beak and toothed snout shapes in 127 species across 120 families of extant birds and extinct non-avian theropods and found that 95% followed the power cascade model. Ancestral state estimation suggests that the power cascade constitutes a fundamental growth pattern of the theropod rostrum, and perhaps all vertebrate rostra. The morphospace defined by the power cascade shows how bird beak shape explores the geometries associated with ecological specializations while adhering to the growth model. We show that the power cascade influences the macroevolutionary exploration of rostrum morphospace, enabling extant birds to inhabit all components of Earth's biosphere.
脊椎动物的喙呈现出显著的形态多样性，以鸟类和非鸟类兽脚亚目恐龙为代表。很少有研究调查潜在的发育过程如何影响喙的形状。幂级联是一种生长模型，描述了喙半径与距喙尖距离之间的对数-对数线性关系。我们测量了现存鸟类和已灭绝非鸟类兽脚亚目恐龙120个科的127个物种的喙和有齿口鼻部形状，发现95%的物种遵循幂级联模型。祖先状态估计表明，幂级联构成了兽脚亚目恐龙喙部的基本生长模式，也许也是所有脊椎动物喙部的基本生长模式。由幂级联定义的形态空间展示了鸟类喙的形状如何在遵循生长模型的同时探索与生态特化相关的几何形状。我们表明，幂级联影响喙部形态空间的宏观进化探索，使现存鸟类能够栖息在地球生物圈的所有区域。
