Friedman, VJohnson, S.C., Lucas, S.G. and Friedman, V. 2002b, Stratigraphic distribution of Ptychodus whipplei, a Late Cretaceous selachian from the United States: Journal of Vertebrate Paleontology, v. 22, supplement to no. 3, p.72A....
2002a, Oldest occurrence of the Cre- taceous shark Ptychodus whipplei Marcou, from the Cenomanian of central New Mexico: New Mexico Geology, v. 24, p. 61.Johnson, S. C. and S. G. Lucas. 2002a . Oldest occurrence of the Cretaceous shark Ptychodus whipplei Mar...
Although similarly developed cusps are observed also in the species Ptychodus rugosus Dixon, 1850 and P.whipplei Marcou, 1858, the material described herein is assigned to Ptychodus altior because of the presence of a narrow cusp with smooth lateral cusp faces. The narrow high-cusped ...
Although similarly developed cusps are observed also in the species Ptychodus rugosus Dixon, 1850 and P.whipplei Marcou, 1858, the material described herein is assigned to Ptychodus altior because of the presence of a narrow cusp with smooth lateral cusp faces. The narrow high-cusped ...