Shimada, K. & Everhart, M.J. & Decker, R. & Decker, P.D. (2010)
A new skeletal remain of the durophagous shark, Ptychodus mortoni, from the Upper Cretaceous of North America: an indication of gigantic body size.
Cretaceous Research, 31(2), 249–254 DOI: 10.1016/j.cretres.2009.11.005