Ankylosaur Remains from the Early Cretaceous (Valanginian) of Northwestern Germany

A fragmentary cervico-pectoral lateral spine and partial humerus of an ankylosaur from the Early Cretaceous (early Valanginian) of Gronau in Westfalen, northwestern Germany, are described. The spine shows closest morphological similarities to the characteristic cervical and pectoral spines of Hylaeosaurus armatus from the late Valanginian of England. An extensive comparison of distal humeri among thyreophoran dinosaurs supports systematic differences in the morphology of the distal condyli between Ankylosauria and Stegosauria and a referral of the Gronau specimen to the former. The humerus fragment indicates a rather small individual, probably in the size range of H. armatus, and both specimens are determined herein as ?Hylaeosaurus sp.. A short overview of other purported ankylosaur material from the Berriasian-Valanginian of northwest Germany shows that, aside from the material described herein, only tracks can be attributed to this clade with confidence at present.

本文记述了产自德国西北部威斯特伐利亚州格罗瑙地区早白垩世（凡兰今阶早期）的一件甲龙类（Ankylosauria）残缺颈胸侧棘及部分肱骨标本。该侧棘的形态与产自英国凡兰今阶晚期的武装棱背龙（Hylaeosaurus armatus）典型颈胸棘最为相似。通过对覆盾甲龙类（Thyreophora）恐龙肱骨远端的广泛对比分析，本研究证实甲龙类与剑龙类（Stegosauria）的远端髁形态存在系统性差异，并将格罗瑙标本归入甲龙类。该肱骨碎片显示其所属个体体型偏小，体型大概率与武装棱背龙相当，本文将本次发现的两件标本暂定为？棱背龙属未定种（?Hylaeosaurus sp.）。本文还简要概述了德国西北部贝里阿斯阶-凡兰今阶中其他据称属于甲龙类的化石材料，结果显示，除本文记述的标本外，目前仅有足迹化石可被可靠地归入该演化支。