IBMS BoneKEy | BoneKEy Watch
New insights into bone structure and bone growth patterns in dinosaurs
DOI:10.1038/bonekey.2014.62
Stein et al. examined previously existing transverse sections of samples from sauropod long bones, and compared the cellular structure with that of new samples obtained perpendicular to the originals using linearly polarized light microscopy. Samples taken from Apatosaurus, Alamosaurus, Camarasaurus and two diplodocids of unknown type were compared.
The results were unexpected; instead of consisting of mostly woven bone, the samples showed that the primary bone was predominantly longitudinal in its organization, similar to the bones found in large-bodied mammals. The authors suggest that future studies of bone in fossil samples should include sections taken in at least two planes to allow the bone types to be differentiated correctly.
Looking at the results using current knowledge of bone formation at the cellular level, the authors propose a new model that may explainx how rapid diametrical bone growth occurred in these dinosaur species. They argue that since the plexiform primary tissues of sauropod long bones show signs of being highly vascularized, sauropods probably grew at similar rates to the large mammals of today.
Editor’s comment: The current understanding of the constitution of sauropod fibrolamellar bone is challenged by this extensive paleohistological investigation of both transverse and longitudinal sections of several taxa. The authors introduce the definition of highly organized primary bone (HOPB) to account for their observations and better classify the outcome of static and dynamic osteogenesis.
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