The Dinosaur with 500 Teeth!

Nigersaurus, sporting its vacuum-like mouth. (Source: University of Chicago)

Across the Mesozoic Era, dinosaurs’ dentition adapted to innumerable diets and ecological niches. The Tyrannosaurus rex’s serrated teeth could max out at 12 inches and the semi-aquatic Spinosaurus carried over 60 teeth in its massive jaws. However, while the carnivores may have been frightening, it was the herbivores who held the largest number of teeth. The duck-billed Hadrosaurus and the horned Triceratops held hundreds of teeth in complex dental batteries, while the sauropod Nigersaurus taqueti holds the record for the most teeth, topping out at over 500. Beneath each tooth were up to eight replacements stacked underneath, allowing the Nigersaurus to continually shed and replenish their dental armory. 

Unusual among dinosaurs, Nigersaurus’ teeth were arranged along a long straight line, forming a shovel-like shape—from there, its teeth would grind up planet matter for digestion. Teeth on both the upper and lower parts of the jaw were convex incisors that pointed outward. Wearing on the teeth suggests they ground against each other during eating. The skull that housed these teeth was made of very delicate bones, with four fenestrate openings. In spite of this, Nigersaurus’ bones were able to take the toll of its abrasive eating style.

Reconstructed Nigersaurus skull at Denver Museum of Nature and Science. (Photo credit: Bernard Sandler)

Nigersaurus’ adaptations to its eating style extend beyond its dental battery. The genus was a part of the sauropod clade, a group of herbivores that used their long necks to consume treetop vegetation. Among the sauropods are some of the largest dinosaurs, but Nigersaurus was relatively small at 30 ft, its short neck allowing it to munch on grasses and low-lying plants. Additionally, Nigersaurus’ inner ears pointed downward, also supporting a body plan geared towards the ground. Because of Nigersaurus’ eating habits, it has been nicknamed the “Mesozoic cow,” thriving in the low floodplains of what is now Niger.

Because of its thin bones, Nigersaurus specimens fossilize poorly and thus few specimens have been discovered. The first was found during a 1960s expedition in Niger headed by paleontologist Philippe Taquet but the scarcity of material meant little was known of Nigersaurus until a Paul Sereno-led expedition in 1997. Much remains unknown about Nigersaurus—its small size for a sauropod has led to much debate over its posture and movements. Still, the dinosaur’s dental configuration makes it unique among dinosaurs, with adaptations at odds with the rest of its clade but fine-tuned to its own environment.

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Read More!

Sereno, Paul C., et al. “Structural Extremes in a Cretaceous Dinosaur.” PloS One, vol. 2, no. 11, 2007, pp. e1230–e1230, https://doi.org/10.1371/journal.pone.0001230.