Ankylosaurus roamed the Earth during the Late Cretaceous period, approximately 68 to 66 million years ago. This large, quadrupedal dinosaur was characterized by a robust body covered in distinctive bony plates, known as osteoderms, and a heavy, club-like tail. It could reach lengths of 6 to 8 meters and weigh between 4.8 and 8 tons.
Ankylosaurus: A Plant-Eating Giant
Ankylosaurus was a herbivore, meaning its diet consisted exclusively of plants. It primarily consumed low-growing vegetation, including ferns, various shrubs, and possibly fruits. It would have needed to consume approximately 60 kilograms (130 pounds) of plant material daily, a quantity comparable to that consumed by a large modern-day elephant. Its broad muzzle suggests it was a non-selective browser, consuming whatever vegetation was readily available in its environment.
Physical Clues to Its Diet
Several anatomical features of Ankylosaurus provide insights into its herbivorous diet. Its teeth were small, leaf-shaped, and peg-like, adapted for stripping foliage. The front part of its jaws was covered by a beak, which would have aided in cropping plants. Research indicates Ankylosaurus possessed a relatively weak bite force, further supporting a diet of softer plant material.
The dinosaur’s broad, barrel-shaped body suggests it housed a large digestive system capable of processing fibrous plant matter. This large gut likely facilitated hindgut fermentation, a process similar to that seen in some modern herbivorous lizards, to break down unchewed plant material. Additionally, the presence of large hyoid bones in ankylosaur skeletons suggests they had long, flexible tongues, useful for gathering vegetation.
The Cretaceous Buffet: Plants of Its Time
During the Late Cretaceous period, the plant landscape was diverse. Gymnosperms, such as conifers and cycads, were common. Ferns and other spore-bearing plants were also abundant, forming a significant part of the low-lying vegetation. Early flowering plants, known as angiosperms, were emerging and spreading across the continent.
As a low-grazer, Ankylosaurus would have primarily fed on this rich variety of ground-level flora. Studies suggest that ankylosaurs generally limited their feeding to vegetation at or below one meter in height.
How Scientists Piece Together Ancient Diets
Scientists employ various methods to reconstruct the diets of extinct animals like Ankylosaurus.
Fossilized Teeth and Jaw Mechanics
Examining fossilized teeth is a fundamental approach, as their shape and structure offer clues about feeding habits; leaf-shaped teeth, for instance, are characteristic of herbivores. Dental microwear analysis, which studies microscopic scratches and pits on tooth surfaces, reveals how food was processed and the texture of the diet. Analyzing the mechanics of an animal’s jaw, including its bite force and range of motion, also provides insights into its dietary adaptations. A weaker bite force and a limited jaw gape are consistent with a diet of softer plant material.
Gastroliths
The discovery of gastroliths, or “stomach stones,” associated with fossil remains can indicate that an animal swallowed stones to aid in grinding tough plant matter within its digestive system. While not definitively linked to Ankylosaurus, gastroliths are found with other herbivorous dinosaurs.
Coprolites
Another direct source of dietary evidence comes from coprolites, which are fossilized feces. These fossilized droppings can contain undigested remnants of food, such as plant fibers or seeds.