Modern amphibians have fully ossified vertebrae with articular processes. All "Panthera" species have an incompletely ossified hyoid bone. Although its hyoid bone is incompletely ossified, it lacks the special morphology of the larynx. The lateral wing of the pterygoid is incompletely and variably ossified. Bone canaliculi are microscopic canals between the lacunae of ossified bone. The authors considered it unlikely these structures were ossified scutes or osteoderms. It can purr as its hyoid bone is ossified. Furthermore, flying fish have developed vertebral columns and ossified caudal complexes. Their skulls are mostly broad and short, and are often incompletely ossified. Its hyoid bone is ossified, making it possible to purr. They had Carnivora-like carnassials but lacked fully ossified auditory bullae. The nasal septum of the woolly rhinoceros was ossified, unlike modern rhinos. Their bones are better ossified and their skeletons stronger than those of amphibians. Ultrasound imaging yields better results defining the anatomy until the cartilage is ossified. In primitive forms, the auditory bullae was not ossified.