Figure 2. Detailed view of the Spinosaurus ‘sail’ and its associated neural spines (after Ibrahim et al. (2014)).

These details were used to determine the relative fractions of the bony and soft tissue components of the sail which were then used to compute the mass and center of mass of the sail. These latter two values were components in the final calculations of the mass, center of mass, and buoyant characteristics of the complete Spinosaurus model. Small white ‘+’s are the centroids of the individual spines. Large black ‘+’ is the centroid of the entire sail. See ‘Methods’ for details of the calculations.