Fig. 8 in Function and evolution of ankylosaur dermal armor

Fig. 8. An osteoderm from an indeterminate ankylosaurid (probably Euoplocephalus), TMP 85.36.218/1, from the Upper Cretaceous Dinosaur Park Formation of Alberta. This specimen was previously described by Scheyer and Sander (2004). A. Photograph of the external surface of the specimen. B. Thin−section of an osteoderm, cut along indicated by dashed lines in A. The thin−section was cut parallel to the ridge of the osteoderms. The bone histology is similar to that of the tail club (TMP 2000.57.03). This osteoderm exhibits a remarkably thin cortex (gray) and a thick cancellous bone (white). Photograph (B1) and interpretive drawing (B2). C, D. Cortical bone tissue of the osteoderm. Detail of the cortex and inner trabecular bone in normal (C) and polarized (D) light; external surface is to the top. The cortex consists of a woven or structural fiber bone with extensive remodeling. Structural fibers are oriented perpendicular in the cortex, but are randomly oriented in the cancellous bone (D).