Stegosaurus, an iconic dinosaur from the Late Jurassic period, is known for its distinctive double row of kite-shaped plates along its back and formidable spiked tail, known as a thagomizer. Despite its armored appearance, this large quadruped was a herbivore. Its unique physical features and immense size were finely tuned for a plant-based diet, allowing it to thrive in its ancient environment.
The Stegosaurus Diet: What They Consumed
Stegosaurus was a dedicated plant-eater, consuming vast quantities of vegetation. It is estimated that a Stegosaurus might have eaten approximately 2 to 3 tons of plants per day.
Its diet primarily consisted of low-growing plants, which were abundant during the Jurassic period. The types of flora available to Stegosaurus included ferns, cycads, and horsetails. Mosses and conifers were also likely components of its diet. Grasses did not exist during the Jurassic period, so Stegosaurus did not consume them.
Uncovering Their Diet: How Scientists Know
Paleontologists piece together the diet of extinct animals like Stegosaurus by examining fossilized clues. The structure of its skull and teeth provides significant evidence. Stegosaurus possessed a long, narrow skull with small, peg-like teeth, not designed for extensive chewing.
The absence of front teeth and extensions in the lower jaw suggest a horny beak, or rhamphotheca, used for cropping plants. Early studies indicated a relatively weak bite force, but more recent computer modeling suggests Stegosaurus had a stronger bite, comparable to modern herbivorous mammals like sheep or cows. This bite force would have allowed it to process a variety of plant materials, including tougher branches up to about 12 mm in diameter.
Further evidence comes from the discovery of gastroliths, or “stomach stones,” found in association with Stegosaurus fossils. These polished stones suggest a digestive aid. The fossil record of plants prevalent during the Late Jurassic also informs scientists about available food sources.
Eating Habits and Adaptations
Stegosaurus employed specific adaptations to consume its plant-based diet effectively. Its small, simple teeth were likely used for snipping or stripping leaves and soft vegetation.
Due to its physical structure, particularly its low-slung head, Stegosaurus was well-adapted for browsing on vegetation close to the ground, likely no higher than one meter. This feeding height limited its access to taller foliage, focusing its diet on the understory plants of the Jurassic forests.
To compensate for its limited chewing ability, Stegosaurus relied on gastroliths in its digestive system. These swallowed stones acted like a grinding mill within the stomach, helping to break down tough plant fibers. Stegosaurus’s teeth show wear patterns indicating tooth-food contact rather than extensive grinding, highlighting the need for this internal mechanism. This internal grinding mechanism allowed Stegosaurus to extract nutrients from the fibrous plant matter it ingested.