Thursday, June 18, 2015

[Paleontology • 2015] Wear Biomechanics in the Slicing Dentition of the Giant horned Dinosaur Triceratops

Fig. 1 Triceratops horridus skeleton and dentitions.
(A) Triceratops skeleton. (B) Transverse view of a dentary (lower jaw) tooth family in this dinosaur whose functional teeth wore to vertical slicing faces. The stippling depicted on the bifid roots is the cementum-like tissue described by Hatcher and colleagues (46).  (C) Naturally worn slicing teeth in the lower jaw of MOR 129734 showing the wear-induced bowing out of the central regions of the occlusal faces of the teeth (arrow) to form fuller-like implements.

Herbivorous reptiles rarely evolve occluding dentitions that allow for the mastication (chewing) of plant matter. Conversely, most herbivorous mammals have occluding teeth with complex tissue architectures that self-wear to complex morphologies for orally processing plants. Dinosaurs stand out among reptiles in that several lineages acquired the capacity to masticate. In particular, the horned ceratopsian dinosaurs, among the most successful Late Cretaceous dinosaurian lineages, evolved slicing dentitions for the exploitation of tough, bulky plant matter. We show how Triceratops, a 9-m-long ceratopsian, and its relatives evolved teeth that wore during feeding to create fullers (recessed central regions on cutting blades) on the chewing surfaces. This unique morphology served to reduce friction during feeding. It was achieved through the evolution of a complex suite of osseous dental tissues rivaling the complexity of mammalian dentitions. Tribological (wear) properties of the tissues are preserved in ~66-million-year-old teeth, allowing the creation of a sophisticated three-dimensional biomechanical wear model that reveals how the complexes synergistically wore to create these implements. These findings, along with similar discoveries in hadrosaurids (duck-billed dinosaurs), suggest that tissue-mediated changes in dental morphology may have played a major role in the remarkable ecological diversification of these clades and perhaps other dinosaurian clades capable of mastication.

Gregory M. Erickson, Mark A. Sidebottom, David I. Kay, Kevin T. Turner, Nathan Ip, Mark A. Norell, W. Gregory Sawyer and Brandon A. Krick. 2015. Wear Biomechanics in the Slicing Dentition of the Giant horned Dinosaur Triceratops. Science Advances. 1(5), e1500055.
DOI: 10.1126/SciAdv.1500055

Triceratops May Have Risen To Dominance Because Of Unique Self-Sharpening Teeth

Gregory M. Erickson, Brandon A. Krick, Matthew Hamilton, Gerald R. Bourne, Mark A. Norell, Erica Lilleodden and W. Gregory Sawyer. 2015. Complex Dental Structure and Wear Biomechanics in Hadrosaurid Dinosaurs. 
338(6103 ); 98-101. DOI: 10.1126/science.1224495