One way paleontologists know a dinosaur was herbivorous is by looking at its teeth. Herbivore dinosaurs typically had flat, conical-shaped teeth that could grind the tough vegetation they ate.
Herbivorous sauropods such as Apatosaurus and Brachiosaurus grew so large because they needed to eat lots of plants to sustain their big sizes. Their long necks were perfect for reaching leaves at the top of trees or grazing on ferns and young shoots.
Protoceratops (pronounced pro-toe-rah-tops) means “first horned face.” It is an early member of the genus Ceratopsian and a ceratopsid, or frilled herbivore. It lived during the late Cretaceous period, in central Asia, alongside ferocious predators like Velociraptor.
Like other ceratopsian dinosaurs, Protoceratops had a neck-covering frill and two greatly enlarged, curved bones called jugals. There is considerable variation in the size of these features between different fossils, which suggests that they could have been used for display or signaling purposes. Also, the size of Protoceratops’s eyes suggests that it was cathemeral—active both during the day and at night.
The head of Protoceratops was large, and its mouth included strong teeth. Its snout or nose had a bump that some researchers believe may have evolved into a horn. But, it is likely that this horn was a feature of the frill rather than the skull itself.
It was smaller than some ceratopsian dinosaurs, and it probably traveled in herds to protect against predators like the Velociraptor. Fossils of young and mature Protoceratops have been found together, suggesting that these herbivorous dinosaurs stayed in herds throughout their lives.
The Protoceratops fossils discovered in Mongolia include one that shows this animal butting a Velociraptor mongoliensis in the chest, which suggests that herding was a common strategy for these herbivores to defend themselves from carnivorous dinosaurs. Fossils of eggs in nests have also been found, which suggests that they laid their eggs in groups and then guarded them.
The Giraffatitan (pronounced Jee-raf-ah-tie-tan) was an herbivorous dinosaur that lived in Africa during the Jurassic period. It was a member of the brachiosaurid family and had long necks. It was similar to the North American Brachiosaurus, but had a number of distinct differences. The differences led to the classification of a new genus and species, Giraffatitan, in 2009. The genus name is based on the resemblance to a giraffe.
The dinosaur was one of the largest land animals to have ever existed and it is estimated that it weighed up to 39.5 short tons. It had a giraffe-like body with large forelimbs and a long neck. Its skull had a tall arch anterior to the eyes that contained bony nares and other openings. It also had “spatulate” teeth that resembled chisels. The first toe on its front foot and the first three toes on its hind feet were clawed.
It is possible that the Giraffatitan walked with a trunk, but this is uncertain. The nares on the top of the head may have been used to amplify calls for inter-species communication. It is thought that these nostrils were closer to the snout than in other sauropods.
The Giraffatitan is known from five partial skeletons, including three skulls. Its fossil was recovered from the Tendaguru formation in Lindi, Tanzania between 1909 and 1912. It lived between 145 and 150 million years ago, during the Kimmeridgian to Tithonian ages of the Jurassic Period. It was the largest of all sauropods and its neck was more than 100 meters (328 ft) long. It ate grass, herbs and other plants and was a grazing herbivore. The Giraffatitan is considered to be the most complete sauropod skeleton to have been discovered to date.
Mamenchisaurus (pronounced “Ma-men-chi-sore-us”) was one of the largest sauropod dinosaurs ever discovered. It lived in the late Jurassic period in what is now China, and grew to be more than 85 feet long. It was primarily an herbivore, eating bracken ferns and trees. Its massive size meant that it would probably not have competed directly with other plant-eaters, but it would have interfered with their habitat and perhaps depleted the available plants due to its movements.
Mamenchisaurus was named in 1952, but it was not formally identified until 1954 by C. C. Young, who studied fossils found on a construction site. This dinosaur has the longest neck of any dinosaur ever known, reaching 49 feet. The neck was supported by 19 vertebrae, some of which were as thin and delicate as eggshells. This neck was probably not very flexible, though it could have swung down to reach tall forest trees.
It is also believed that the Mamenchisaurus had blunt, paddle-shaped teeth for chewing thick plant material. This distinguishes it from Diplodocidae sauropods, which had pin-shaped teeth. The Mamenchisaurus was similar to the Diplodocus in some ways, but had distinct differences, such as its smaller head and fewer neck vertebrae.
Like all sauropods, Mamenchisaurus was likely very slow and lumbering. Its enormous size would have impacted its environment in many ways, destroying and damaging vegetation with its movements and even eroding the ground with its weight. Its behavior was largely indifferent toward other animals, but it may have displayed some aggressive behaviors if threatened by another sauropod or by a herd of young animals. In the video game Jurassic World Evolution, a Mamenchisaurus is portrayed as wandering through forests and foraging on trees and ferns.
Like most small basal members of the Ornithopoda, Atlascopcosaurus had two different kinds of teeth to grind up its diet of tough ferns and horsetails. The dinosaur probably used its long, flexible tail to balance out its center of gravity while running from predators. Its tail was stiffened by ossified tendons, which are similar to the way a cantilever bridge works.
Fossils of Atlascopcosaurus have been found at Dinosaur Cove East, on the south coast of Victoria, in sediments of the Eumeralla Formation. The fossils suggest that the dinosaur was about 6.5- to 13-ft long. It was small, and it would have been able to run very quickly. This might have been an advantage, as Atlascopcosaurus likely shared its habitat with larger predators such as the Leaellynasaura.
The dinosaur’s skull was thin and short, with a large opening for the mouth. Its jaws were relatively wide and had high-crowned, many-ridged teeth. These were designed to eat the tough ferns and horsetails that covered Australia’s coastline during the Early Cretaceous period.
Atlascopcosaurus is an example of the diversity that existed among small ornithopods in Australia during the Early Cretaceous. Other small ornithopods of the region include Qantasaurus intrepidus and Diluvicursor pickeringi, both from the Otway Coast, and Leaellynasura from the Bass Coast.
In 1988, Atlascopcosaurus was assigned to the clade Hypsilophodontidae, but this group has since been deemed an unnatural paraphyletic. Atlascopcosaurus is now classified as a member of the more general Ornithopoda. Its basal position and distinctive features, such as a distinctly cheek area along the maxilla and dentary with predentary beaks and occluding grinding teeth in the upper and lower jaws, suggest that it was a member of the most primitive Ornithopoda.
Archaeoceratops was a small basal ceratopsid that lived in China during the early Cretaceous. It was about 1 meter long and was closely related to the psittacosaurid dinosaurs. It was probably bipedal. Archaeoceratops had a very large head compared to its body size, but it did not have horns like later ceratopsian dinosaurs. It also had a very small bony frill on its head.
Archaeocepsids were herbivorous dinosaurs. They probably ate plants like bamboo and other reeds. They did not have teeth, but they could chew and grind food with their skulls.
The study of ceratopsian jaw mechanics is difficult because well-preserved specimens are rare. In order to determine the efficiency of a ceratopsian jaw, the researchers measured the leverage of its mandibles. The results showed that the bite force was greatest at the jugal and lowest at the predentary. This suggests that a ceratopsian’s mouth was efficient and capable of processing large volumes of food.
The jugal is elongate and shallow with a dorsal edge that is sub-parallel to the ventral surface in lateral view. This feature is similar to the jugal of other basal neoceratopsians, including Psittacosaurus and Archaeoceratops. The jugal carries a low horn.
The genus Archaeoceratops means “ancient horned face.” The type species, A. oshimai, was found in the Xinminbao Group of the Gongpoquan Basin in north central China. It is known from a partial skull and incomplete skeleton. It was named by Dong Zhiming and Yoshizuma Azuma in 1997. It was the first basal neoceratopsian discovered in China. It is believed to be closely related to the psittacosaurids, but unlike many later horned dinosaurs, it had a small boney frill on its head and no horns.