ABSTRACT

Tsintaosaurus spinorhinus is famous for the unique rod-like nasal spine, but there has been a long debate about whether its nasal spine is hollow, since it is difficult to examine the nasal inside through direct observation. Here, we used a high-resolution CT scan to reveal the interior structure of the nasal spine and re-observed the holotype and paratype of Tsintaosaurus spinorhinus. By the direct observation and CT scan, we provide new information about the nasal spine of Tsintaosaurus spinorhinus, and our result shows the rod-like nasal spine of Tsintaosaurus spinorhinus is a solid sandwich structure, rather than a hollow tubular structure. There is a significant fracture between the rod-like process and the base of the nasal, and if the two processes fit together, the nasal spine would have been more inclined rostrally in life. The new cranial information collected through the direct observation and CT scan reveals that the narrow strip surrounded by the nasals and frontals is formed by a longitudinal median groove filled with sediment, indicating the possible presence of the frontal-nasal fontanelle in younger juveniles.