Abstract

The Upper Jurassic Lourinhã Formation is well known for its rich assemblage of fossil vertebrates. In this formation, ornithopod dinosaurs are represented by two iguanodontian species, Eousdryosaurus nanohallucis and Draconyx loureiroi. We recently became aware of unreported material belonging to the holotype of Draconyx loureiroi, consisting of partially articulated manual elements. We here re-describe the holotype specimen ML 357, including the newly discovered material. The specimen was subjected to CT-scanning and its surface data used to assess anatomical characters. Linear measurements of metatarsal III were used to estimate the body length of the specimen. The Draconyx loureiroi holotype was included in two datasets and analysed with maximum parsimony and Bayesian inference approaches to estimate evolutionary rates among Iguanodontia. We present evidence that Draconyx loureiroi is a valid taxon nested in Styracosterna and is clearly diagnosable by a unique combination of characters. Both maximum parsimony and Bayesian inference indicate high evolutionary rates across the Jurassic/Cretaceous transition for the base of Iguanodontia. Length estimation suggests that Draconyx loureiroi was a relatively small, bipedal and possibly cursorial animal. Given its basal phyletic position, we interpret this bauplan was the ancestral condition for Styracosterna, that only later in the Cretaceous evolved into giant quadrupedal forms.

中文翻译：

---

Draconyx loureiroi (Ornithischia: Iguanodontia) 正模标本的重新评估和新材料为拇指尖恐龙的进化速度和模式提供了见解

摘要

上侏罗纪 Lourinhã 组以其丰富的脊椎动物化石组合而闻名。在这种地层中，鸟脚类恐龙以两种禽龙类物种为代表，Eousdryosaurus nanohallucis和Draconyx loureiroi。我们最近发现了属于Draconyx loureiroi正模标本的未报告材料，由部分铰接的手工元素组成。我们在这里重新描述了正模标本 ML 357，包括新发现的材料。对标本进行 CT 扫描，其表面数据用于评估解剖特征。跖骨 III 的线性测量值用于估计样本的体长。Draconyx loureiroiholotype 被包含在两个数据集中，并用最大简约法和贝叶斯推理方法进行分析，以估计禽齿兽的进化率。我们提供的证据表明Draconyx loureiroi是嵌套在 Styracosterna 中的有效分类单元，并且可以通过独特的字符组合清楚地诊断。最大简约性和贝叶斯推断都表明，禽龙类基部在侏罗纪/白垩纪过渡期间的进化率很高。长度估计表明，Draconyx loureiroi是一种相对较小的双足动物，可能是粗野的动物。考虑到它的基础种系位置，我们解释这个小动物是 Styracosterna 的祖先条件，它只是在白垩纪后期演变成巨大的四足动物形式。