Ankylosaurian body armor function and evolution with insights from osteohistology and morphometrics of new specimens from the Late Cretaceous of Antarctica

The body armor of ankylosaurians is a unique morphological feature among dinosaurs. Despite being studied for decades, paleohistological analyses have only started to uncover the details of its function. Yet, there has been an overall bias toward sampling ankylosaurian remains from the Northern Hemisphere and limited quantitative studies on the morphological and functional evolution. Here, we describe new ankylosaurian materials recovered from the Late Cretaceous of Antarctica that, in combination with data compiled from the literature, reveal new insights into the evolution of the ankylosaurian body armor. Based on histological microstructure and phylogenetic results, the new Antarctic material can be assigned to Nodosauridae. This group shares the absence/poor development of the basal cortex and highly ordered sets of orthogonal structural fibers in the superficial cortex. Our morphospace analyses indicate that large morphological diversity is observed among both nodosaurids and ankyl..., Material 
The figures of specimens CAV-4 and 5 before the paleohistological sections are available in Supplementary Fig. 1. There is no figure for the specimen CAV-10.
Statistical Analyses
The dataset compiled from the literature for our linear morphometric analyses is available in the file “Dataset_osteoderms.xlsx”. The compiled specimens are listed in Table 1. The entire dataset of PAST files to osteoderms is available in “Dataset_osteoderms.dat”. 
The abbreviations and description of variables used in both datasets are: B, thickness of the osteoderm basal cortex; BI, basal index (BI = 100B/T); CI, cortical index (CI = 100*(S + B)/T); Co, thickness of the osteoderm core; CoI, core index (CoI = 100Co/T); Group, main group that the specimens are assigned (Ankylosauridae, Nodosauridae or Titanosauria); Osteoderm, shape of the osteoderm; Group+osteodem, classification joining main group and shape of osteoderm; S, thickness of the osteoderm superficial cortex; S+B, sum of osteoderm superfi...,

甲龙类（ankylosaurians）的体表装甲是恐龙中独一无二的形态特征。尽管该类群已被研究数十年，但古组织学分析（paleohistological analyses）仅在近年才逐步揭示其功能细节。然而过往研究整体存在偏向于采集北半球甲龙类遗骸的偏差，且针对其形态与功能演化的定量研究较为匮乏。
本次研究描述了一批采自南极洲晚白垩世（Late Cretaceous）地层的甲龙类新材料，结合文献汇编的数据，这些新材料为甲龙类体表装甲的演化提供了全新认知。基于组织学微观结构与系统发育分析结果，这批南极新材料可归入结节龙科（Nodosauridae）。该类群具有基皮层（basal cortex）缺失或发育不良、浅皮层（superficial cortex）内存在高度规整的正交结构纤维束的共同特征。我们的形态空间（morphospace）分析显示，结节龙类与甲龙类群均展现出丰富的形态多样性[原文截断]。
标本CAV-4与CAV-5在古组织学切片制作前的成像图详见补充图1（Supplementary Fig.1），标本CAV-10未附相关图像。
统计分析
本研究线性形态计量分析所依托的文献汇编数据集，可在文件"Dataset_osteoderms.xlsx"中获取，所纳入的标本详见表1。针对骨板（osteoderms）的全部PAST格式数据集可在"Dataset_osteoderms.dat"中获取。
两个数据集所使用的缩写与变量含义如下：B，骨板基皮层厚度；BI，基皮层指数（BI = 100B/T）；CI，皮层指数（CI = 100*(S + B)/T）；Co，骨板核心厚度；CoI，核心指数（CoI = 100Co/T）；Group，标本所属大类群（甲龙科（Ankylosauridae）、结节龙科（Nodosauridae）或泰坦龙类（Titanosauria））；Osteoderm，骨板形态；Group+osteodem，结合大类群与骨板形态的分类项；S，骨板浅皮层厚度；S+B，骨板浅皮层与基皮层厚度之和[原文截断]