Reflectivity of convex vs. concave surfaces from A new fossil dolphin Dilophodelphis fordycei provides insight into the evolution of supraorbital crests in Platanistoidea (Mammalia, Cetacea)

3D models of USNM 214911 (A), Pomatodelphis (B) and Platanista (C) with the inner faces of their supraorbital crests highlighted in blue. Diagrams of reflective properties of convex (D) and concave (E) surfaces, with incoming sound waves in red and outgoing sound waves in orange. Note that these diagrams (D,E) are not representative of how sound is reflecting off the supraorbital crests in platanistoids, since the phonic lips (where sound is generated) are located posterodorsal of the crests.