In the time of the dinosaurs the earth was a much different place than it is today, but the food chain was still occupied by creatures categorized as being either carnivorous, herbivorous, or omnivorous. In that respect, the circle of life is much the same as it is today, with predators and prey helping to sustain a balance between the two. The carnivorous dinosaurs like the Tyrannosaurus Rex only ate meat while the herbivores, who accounted for 65 % of the population, consumed only plants and vegetation. Omnivorous dinosaurs such as the Ornithomimes ate both meat and plants just as humans do today, but there are only a few confirmed omnivorous dinosaurs. Many of these omnivorous dinosaurs earned that distinction by eating eggs or insects, as well as consuming plants.
What we know about the diet of dinosaurs comes from fossil evidence; including Coprolites, or fossilized dung. There have also been instances when the fossilized remains of small creatures have been found in the stomachs of larger creatures, hinting at the relationship between predator and prey. Although the temperature isn’t radically different now than it was during the time of dinosaurs, the plant life was quite varied. Very little of the earth’s plant life, which was the source of nourishment for sixty-five percent of the dinosaur population, would look familiar in comparison with the earth as we know it today.
With the vast majority of dinosaurs being herbivores, the amount of plant life needed to sustain them was staggering and many dinosaurs led a nomadic life, migrating constantly in search of food. A lush, productive planet was essential to ward off starvation of not only the grazing herbivorous animals, but the predators that hunted them as well. Unfortunately for the herbivores, during much of the late Mesozoic area plant life on earth was relatively sparse.
As is the case with their armor plating, horns, and other prehistoric weapons, the teeth of the dinosaurs were as equally evolved when it came time for them to serve their purpose. While the herbivores had flat, dull teeth that were made predominately for chewing, the carnivores had sharpened, serrated, and long teeth that were designed for tearing their food. While they only made up thirty-five percent of the population the carnivorous dinosaurs incite the imagination with wonder and curiousity. The ferocious Velociraptor, the powerful Tyrannosaurs Rex, images of them are burned into our brains as the alpha hunters of the day.
For carnivores, the few omnivores that have been confirmed, and the cannibals, their source of food was basically anything that they could capture and kill. These well-equipped predators often brought down animals that were much larger than them by using their well honed teeth andc laws to tear and wound their prey. Dinosaurs such as the Tyrannosaurus Rex would scavenge for food as well, often eating the carcasses of other dinosaurs that it found. Other examples of carnivorous dinosaurs are the Megalosaurus, Utahraptor, and the Albertosaurus, all of which relied upon their tremendous power and their sharpened teeth and claws to hunt their prey.
The herbivores of the Mesozoic era consumed vast quantities of food, and grazed across many miles of sparse flatlands in search of sustenance. The plant life on earth didn’t begin to evolve into the forms of flowering plants that we know today until the end of the Cretaceous period, and their primary meal consisted of conifers, the tough-leaved Cycadophytes, and seed ferns. More interesting than their choice of food, was the way that some of them digested what they consumed. Some large herbivores would swallow small stones known today as gastroliths. These stones helped the creature digest the dense vegetation by shredding it as the stone moved around the abdominal tract while the creature moved. The ankylosaurus had another interesting evolutionary development, the presence of fermentation chambers in its stomach that helped it to help break down plant material.
Other plants that were included in the herbivores diet were the Gingkos, which grew at high altitude and lost their leaves during the cold season. The Pteridophytes were a more available choice however, and were a fast growing plant species. For the herbivores the Pteridophytes made up the majority of their diet. Fast growing and resilient, the Pteridophytes included such plant life as horsetails and lycopods, and they were a readily available food source.