Bone histology and growth of the prosauropod dinosaur <i>Plateosaurus engelhardti</i> MEYER, 1837 from the Norian bonebeds of Trossingen (Germany) and Frick (Switzerland)

Abstract

Predominately long- and flat bones of the prosauropod <i>Plateosaurus engelhardti</i> from the Norian localities of Trossingen and Frick were sampled for paleohistological study. Both localities yield rich material of adult individuals with a body size of 4.70 m to 10 m. <br /> Altogether 50 bones from approximately 27 individuals were sampled by different methods (coring, cross sectioning, analysis of existing fracture surfaces). Most bones consist of the laminar fibro-lamellar complex, always cyclically interrupted by lines of arrested growth (LAGs). In some bones, the laminar fibro-lamellar complex changed in the exterior cortex to lamellar-zonal bone, later grading into avascular lamellar bone. Thus, growth was clearly determinated in <i>P. engelhardti</i>. <br /> Like most other dinosaurs <i>Plateosaurus engelhardti</i> shows high growth rates, indicating an advanced (“dinosaurian”) physiology. On the other hand, <i>Plateosaurus engelhardti</i> shows a strong dependency on environmental conditions. Additionally, its final size is represented by a very broad range (between 6.5 m to 10 m). Both reflect a more reptilian growth pattern as is known from other dinosaurs. It marks the basal status of <i>Plateosaurus engelhardti</i>. Thus, in <i>Plateosaurus</i> the foundation is seen for the evolution of gigantism in sauropods.