Fig. 3 in Bone microstructure and relative age of the holotype specimen of the diplodocoid sauropod dinosaur Suuwassea emilieae

Fig. 3. Histologic structures visible in the tibia of the holotype (ANS 21122) of the diplodocoid sauropod Suuwassea emilieae Harris and Dodson, 2004, Morrison Formation, Late Jurassic, photographed under plane-polarized light. A. Successive growth cycles in the caudolateral region of the bone. Brackets indicate successive highly and poorly vascularized zones. Highly vascularized zone with dense primary osteons (right), followed by a poorly vascularized annulus (middle). The leftmost region shows the subsequent zone characterized by higher vascularization (outermost cortex to left). B. The high density of secondary osteons (outlined in green) in the medial inner cortex, showing overprinting by a second generation (green arrow). Additionally, primary osteons are visible between secondary osteons showing that the bone is not completely remodeled (blue arrow). C. A cluster of secondary osteons in the outer cortex of the craniomedial region. This cluster is surrounded by primary osteons. D. Outer cortex of the caudolateral region, showing the LAG (line of arrested growth) (arrow) associated with the fourth annulus. E. Two LAGs in the outermost cortex of the lateral region. F. Primary osteons in the outermost cortex of the craniolateral region leading up to the periosteal surface of the bone.