Micrographs of longitudinal thin sections of Nothosaurus mirabilis long bones. A, proximal epiphysis of N. mirabilis humerus (SIPB R 54/2) in polarized light. The section shows the growth plate below the articular cartilage. The endochondral bone is very thin at the proximal epiphysis, and there are only a few endochondral trabeculae, which have mostly been coated by endosteal bone. B-E, proximal epiphysis of N. mirabilis femur (SIPB R 54/1). B and C show the growth plate below the articular cartilage in normal transmitted and in polarized light. The trabeculae of the growth plate consist of cartilage covered by endochondral bone. D-E, trabeculae in deeper cortical regions of the femur in normal transmitted light (D) and polarized light (E). The trabeculae still have a calcified cartilage core but were subject to remodeling activity. Abbreviations: eb, endosteal bone.