Dental histology of the sauropod dinosaurs Camarasaurus and Diplodocus.
Thin sections of Camarasaurus (A, C) and Diplodocus (B, D) premaxillary teeth showing incremental lines of von Ebner (white arrowheads) in dentin. Teeth are oriented with their long axis horizontal and the occlusal surface directed to the right. A shows the tip of tooth 3iii of Camarasaurus, and B shows the tip of tooth 4iv of Diplodocus. C and D are enlarged images of one ‘limb’ of tooth 3ii and 4iii, respectively. Abbreviations: edj, enamel-dentin junction; en, enamel; pc, pulp cavity. [planned for page width].

Cladogram of sauropodomorphs showing the optimization of key features related to elevated tooth replacement rates.
The light gray field indicates taxa that have at least three replacement teeth at each tooth position; dark gray field encapsulates taxa that have narrow tooth crowns. Silhouettes along the top of the cladogram show the number and size of replacement teeth in one tooth position. These include (from left to right): Patagosaurus (MPEF-PV 1670), Mamenchisaurus [47], Diplodocus (this study), Nigersaurus [Sereno, Wilson, Witmer, Whitlock, Maga, Ide and Rowe, unpublished data], Camarasaurus (this study), and the Río Negro titanosaur (MPCA-79) [48]. Number of replacement teeth is unknown in Brachiosauridae, but the taxon is optimized to have had at least three. Cladogram based on [30] with the addition of Tazoudasaurus [49] and Bonitasaura [50]. [planned for column width].