Okay, since Twitter hasn't had enough Spinosaurus stuff over the past few weeks, Ima spend #FossilFriday diving into whether or not #Spinosaurus had lips, from a completely non-osteological perspective! First, why have lips? Lips serve two big functions in tetrapods: first, as protection against tooth desiccation (retaining moisture), and also for hydrodynamics in whales and dolphins, by smoothing out their profile. (2nd image: Florian Graner)