Limits...
A nomenclature for vertebral fossae in sauropods and other saurischian dinosaurs.

Wilson JA, D'Emic MD, Ikejiri T, Moacdieh EM, Whitlock JA - PLoS ONE (2011)

Bottom Line: 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 table, and "tertiary landmarks," which further delineate a given fossa.The proposed nomenclatural system for lamina-bounded fossae adds clarity to descriptions of complex vertebrae and allows these structures to be sourced as character data for phylogenetic analyses.These anatomical terms denote potentially homologous pneumatic structures within Saurischia, but they could be applied to any vertebrate with vertebral laminae that enclose spaces, regardless of their developmental origin or phylogenetic distribution.

View Article: PubMed Central - PubMed

Affiliation: Museum of Paleontology and Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan, United States of America. wilsonja@umich.edu

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 table, and "tertiary landmarks," which further delineate a given fossa.

Conclusions/significance: The proposed nomenclatural system for lamina-bounded fossae adds clarity to descriptions of complex vertebrae and allows these structures to be sourced as character data for phylogenetic analyses. These anatomical terms denote potentially homologous pneumatic structures within Saurischia, but they could be applied to any vertebrate with vertebral laminae that enclose spaces, regardless of their developmental origin or phylogenetic distribution.

Show MeSH

Related in: MedlinePlus

Representative vertebrae of Mamenchisaurus youngi.Anterior (top), left lateral (middle), and posterior (bottom) views of anterior cervical (cv 9), posterior cervical (cv 17), anterior dorsal (dv 2), posterior dorsal (dv 8), and anterior caudal (ca 1) vertebrae. Specimens come from a single individual (holotype ZDM 0083) and are to scale. Posterior view of cv 9 and anterior views of cv 9, cv 17, and dv 8 not available; anterior view of dv 7 used for dv 8. Important changes along the column include the appearance of a pcpl and the division of the cdf into a pacdf and a cpaf. Images are modified from [33]:figs. 15, 17, 20, 26, 30). Abbreviations and color scheme as in Figure 7.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3046170&req=5

pone-0017114-g008: Representative vertebrae of Mamenchisaurus youngi.Anterior (top), left lateral (middle), and posterior (bottom) views of anterior cervical (cv 9), posterior cervical (cv 17), anterior dorsal (dv 2), posterior dorsal (dv 8), and anterior caudal (ca 1) vertebrae. Specimens come from a single individual (holotype ZDM 0083) and are to scale. Posterior view of cv 9 and anterior views of cv 9, cv 17, and dv 8 not available; anterior view of dv 7 used for dv 8. Important changes along the column include the appearance of a pcpl and the division of the cdf into a pacdf and a cpaf. Images are modified from [33]:figs. 15, 17, 20, 26, 30). Abbreviations and color scheme as in Figure 7.

Mentions: Below we provide examples demonstrating how nomenclature for vertebral fossae can be applied to a broad sampling of sauropod dinosaurs.


A nomenclature for vertebral fossae in sauropods and other saurischian dinosaurs.

Wilson JA, D'Emic MD, Ikejiri T, Moacdieh EM, Whitlock JA - PLoS ONE (2011)

Representative vertebrae of Mamenchisaurus youngi.Anterior (top), left lateral (middle), and posterior (bottom) views of anterior cervical (cv 9), posterior cervical (cv 17), anterior dorsal (dv 2), posterior dorsal (dv 8), and anterior caudal (ca 1) vertebrae. Specimens come from a single individual (holotype ZDM 0083) and are to scale. Posterior view of cv 9 and anterior views of cv 9, cv 17, and dv 8 not available; anterior view of dv 7 used for dv 8. Important changes along the column include the appearance of a pcpl and the division of the cdf into a pacdf and a cpaf. Images are modified from [33]:figs. 15, 17, 20, 26, 30). Abbreviations and color scheme as in Figure 7.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3046170&req=5

pone-0017114-g008: Representative vertebrae of Mamenchisaurus youngi.Anterior (top), left lateral (middle), and posterior (bottom) views of anterior cervical (cv 9), posterior cervical (cv 17), anterior dorsal (dv 2), posterior dorsal (dv 8), and anterior caudal (ca 1) vertebrae. Specimens come from a single individual (holotype ZDM 0083) and are to scale. Posterior view of cv 9 and anterior views of cv 9, cv 17, and dv 8 not available; anterior view of dv 7 used for dv 8. Important changes along the column include the appearance of a pcpl and the division of the cdf into a pacdf and a cpaf. Images are modified from [33]:figs. 15, 17, 20, 26, 30). Abbreviations and color scheme as in Figure 7.
Mentions: Below we provide examples demonstrating how nomenclature for vertebral fossae can be applied to a broad sampling of sauropod dinosaurs.

Bottom Line: 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 table, and "tertiary landmarks," which further delineate a given fossa.The proposed nomenclatural system for lamina-bounded fossae adds clarity to descriptions of complex vertebrae and allows these structures to be sourced as character data for phylogenetic analyses.These anatomical terms denote potentially homologous pneumatic structures within Saurischia, but they could be applied to any vertebrate with vertebral laminae that enclose spaces, regardless of their developmental origin or phylogenetic distribution.

View Article: PubMed Central - PubMed

Affiliation: Museum of Paleontology and Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan, United States of America. wilsonja@umich.edu

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 table, and "tertiary landmarks," which further delineate a given fossa.

Conclusions/significance: The proposed nomenclatural system for lamina-bounded fossae adds clarity to descriptions of complex vertebrae and allows these structures to be sourced as character data for phylogenetic analyses. These anatomical terms denote potentially homologous pneumatic structures within Saurischia, but they could be applied to any vertebrate with vertebral laminae that enclose spaces, regardless of their developmental origin or phylogenetic distribution.

Show MeSH
Related in: MedlinePlus