a nomenclature for vertebral fossae in sauropods and other saurischian dinosaurs命名为椎窝在蜥脚类恐龙和其他蜥恐龙.pdfVIP

A Nomenclature for Vertebral Fossae in Sauropods and Other Saurischian Dinosaurs Jeffrey A. Wilson*, Michael D. D’Emic, Takehito Ikejiri, Emile M. Moacdieh, John A. Whitlock Museum of Paleontology and Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan, United States of America Abstract Background: The axial skeleton of extinct saurischian dinosaurs (i.e., theropods, sauropodomorphs), like living birds, was pneumatized by epithelial outpocketings of the respiratory system. Pneumatic signatures in the vertebral column of fossil saurischians include complex branching chambers within the bone (internal pneumaticity) and large chambers visible externally that are bounded by neural arch laminae (external pneumaticity). Although general aspects of internal pneumaticity are synapomorphic for saurischian subgroups, the individual internal pneumatic spaces cannot be homologized across species or even along the vertebral column, due to their variability and absence of topographical landmarks. External pneumatic structures, in contrast, are defined by ready topological landmarks (vertebral laminae), but no consistent nomenclatural system exists. This deficiency has fostered confusion and limited their use as character data in phylogenetic analysis. Methodology/Principal Findings: We present a simple system for naming external neural arch fossae that parallels the one developed for the vertebral laminae that bound them. The nomenclatural system identifies fossae by pointing to reference landmarks (e.g., neural spine, centrum, costal articulations, zygapophyses). We standardize the naming process by creating tripartite names from ‘‘primary landmarks,’’ which form the zygodiapophyseal table, ‘‘secondary landmarks,’’ which orient with respect to that tab