An omnivore consumes both plants and meat. While many dinosaurs were strict herbivores or carnivores, some possessed a mixed diet. This dietary flexibility allowed certain dinosaurs to adapt to various environments and food availability.
Dinosaurs That Ate Both
Several dinosaur species were omnivores, exhibiting physical characteristics that supported a varied diet. Well-known examples include members of the Ornithomimosauria group, often called “ostrich dinosaurs,” such as Ornithomimus, Gallimimus, and Deinocheirus.
Ornithomimus, a swift bipedal dinosaur, had a toothless beak, suggesting it was not strictly carnivorous. Gastroliths, or stomach stones, found in related ornithomimids indicate a diet that included plant matter. They likely also consumed insects, crustaceans, eggs, and small animals.
Gallimimus, another ostrich-like dinosaur, also had a toothless beak. Some scientists propose it was used for filter-feeding, while others suggest it processed tough plant material. Its diet also included small mammals, lizards, eggs, and insects, pointing to an opportunistic omnivorous feeding strategy.
Deinocheirus, a larger ornithomimosaur, had a duck-billed skull and a hump. Its diet included plants and fish, with fossilized fish scales and gastroliths found with specimens. Its large claws, once thought for hunting, might have been used for digging plants or foraging in mud.
Oviraptor, a bird-like dinosaur, was initially misidentified as an egg thief but later evidence showed it likely brooded its own eggs. Its strong, toothless beak and jaws, suited for crushing hard foods like mollusks, also allowed it to consume plants, seeds, insects, and small animals. These examples highlight that omnivory was a successful dietary niche among diverse dinosaur groups.
How Scientists Determine Dinosaur Diets
Paleontologists use various lines of evidence to reconstruct the diets of extinct dinosaurs. One primary method involves analyzing fossilized teeth, as their shape and wear patterns provide clues about the food they processed. Sharp, serrated teeth indicate a meat-eating diet, while flat, grinding teeth suggest plant consumption, and a mix of both points to omnivory.
Beyond teeth, the structure of dinosaur jaws offers insights into how food was processed, such as whether it was torn or ground. Direct evidence, though rare, can come from fossilized stomach contents, revealing a dinosaur’s last meal. Coprolites, or fossilized dung, can also contain identifiable traces of plants or animal remains. Additionally, gastroliths, swallowed stones found with some dinosaur fossils, suggest the animal used them to grind tough plant material, similar to modern birds. Analyzing chemical signatures, like calcium isotopes in tooth enamel, can also reveal the types of food consumed.
Why Some Dinosaurs Were Omnivores
The evolution of an omnivorous diet offered several significant advantages. This dietary flexibility allowed dinosaurs to adapt to a wider range of environments, as they were not restricted to a single food source. Consuming both plants and animals provided greater food security, especially during times of scarcity.
Omnivory also ensured access to a broader spectrum of nutrients, supporting growth and survival. This adaptability and resourcefulness likely contributed to their success and resilience throughout the Mesozoic Era. The ability to exploit diverse food sources could have given omnivorous dinosaurs an edge in survival, allowing them to thrive in varied ecological niches.