A new look at <i>Crocodylopodus meijidei</i>: implications for crocodylomorph locomotion

A review of the type material of the crocodylomorph ichnotaxon <i>Crocodylopodus meijidei</i> Fuentes Vidarte and Meijide Calvo, 2001 from the Berriasian of Spain is carried out. The review allows a better characterization of this type ichnotaxon and provides interesting new data on the candidate trackmakers and especially on their locomotion. Three different size classes possibly related to different ontogenetic states or sexual dimorphism of the same small- to medium-sized crocodylomorph trackmaker are distinguished. Morphological differences within the sample such as digital impression lengths might be a consequence of differences in allometric growth, assuming similarities with extant crocodylians. Other differences are a consequence of variation in the morphological quality and mode of preservation across the sample. Some trackway features (intermediate-gauge trackways with high pace angulation, absence of tail, belly or drag marks) indicate the trackmakers, presumed neosuchian crocodylomorphs, were walking in a ‘high-walk’ mode with a semi-erect posture at a moderate speed. The trackmaker may have walked with more erect limb posture and with the center of mass located more anteriorly than occurs in extant species, albeit not as erect as quadrupedal animals such as mammals or other extinct archosaurs including trackmakers of other crocodylomorph ichnotaxa (e.g., <i>Batrachopus</i>).

本研究对产自西班牙贝里亚斯阶（Berriasian）的鳄形类（crocodylomorph）足迹化石分类单元（ichnotaxon）*Crocodylopodus meijidei*（Fuentes Vidarte & Meijide Calvo, 2001）的模式标本开展系统厘定工作。本次厘定完善了该模式足迹化石分类单元的特征描述，并为其潜在造迹者，尤其是其运动方式，提供了颇具价值的全新数据。

研究识别出3个不同的尺寸类群，其可能对应同一中小型鳄形类造迹者的不同个体发育阶段（ontogenetic states）或性别二态性（sexual dimorphism）。样本内存在的形态差异（如趾印长度差异），若参考现生鳄类（extant crocodylians）的生长模式，可归因于异速生长（allometric growth）带来的变化；其余形态差异则源于样本间保存质量与埋藏方式的差异。

部分足迹道（trackway）特征——步角（pace angulation）较大的中等宽度足迹道、无尾迹、腹痕或拖拽痕迹——表明，被推测为新鳄类（neosuchian）的造迹者，当时以半直立姿态采取“高行走”（high-walk）模式，运动速度中等。该造迹者的四肢直立程度相较于现生鳄类更高，重心位置也更靠前，但仍未达到哺乳动物或其他已灭绝主龙类（archosaurs）的四足直立动物水平，例如其他鳄形类足迹化石分类单元的造迹者——如*Batrachopus*（蛙足迹属）。

搜集汇总

背景与挑战

背景概述

该数据集重新审视了西班牙Berriasian时期的鳄形类足迹分类单元Crocodylopodus meijidei的模式材料，旨在改进其类型特征并提供关于足迹制造者运动的新见解。研究区分了三种大小类别，可能与发育状态或性别二态性相关，并分析足迹特征表明足迹制造者以“高步态”方式行走，具有半直立姿势和中等速度。这些发现有助于理解鳄形类的运动演化，并包含3D模型和补充数据等文件支持分析。