Does morphology reflect osteohistology-based ontogeny? A case study of Late Cretaceous pterosaur jaw symphyses from Hungary reveals hidden taxonomic diversity

With a single complete mandible and 56 mandibular symphyseal fragments of various sizes, the Late Cretaceous Hungarian azhdarchid material has been considered one of the most extensive monospecific pterosaur assemblages in the world. Representing a broad size range, these elements have been thought to demonstrate a developmental series of Bakonydraco galaczi. As such, they were ideal to test whether absolute size and/or morphology reliably indicate relative ontogenetic stages in this pterosaur. Forty-five specimens were selected for multivariate morphometrics and classified into four size classes. After acquiring the morphometric data set, we thin-sectioned eight symphyses representing all size groups and classified them into relative ontogenetic stages based on qualitative microstructural inspection prior to quantitative histological analyses. Microstructural characters suggestive of developmental state were then quantified for intra- and interindividual uni- and multivariate analyses ...

此次发现的晚白垩世匈牙利神龙翼龙类（azhdarchid）标本包含1具完整下颌骨与56件不同尺寸的下颌联合骨碎片，被认为是全球范围内保存最完整的单种翼龙类组合之一。这批标本涵盖了广泛的尺寸范围，被认为展现了巴科尼龙（Bakonydraco galaczi）的发育序列。正因如此，这批标本成为验证该翼龙类的绝对尺寸与/或形态是否能可靠反映相对个体发育阶段的理想材料。研究选取了45件标本进行多变量形态测量，并将其划分为4个尺寸等级。获取形态测量数据集后，我们对代表所有尺寸组的8件下颌联合骨标本进行了薄切片制作，并在开展定量组织学分析前，通过微观结构的定性观察将其划分为相对个体发育阶段。随后，研究人员对反映发育状态的微观结构特征进行量化，以开展个体内、个体间的单变量与多变量分析……