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Dinosaurs come in all shapes and sizes, but scientists separate them into two groups based on hip structure: the Order Ornithischia and the Order Saurischia. Harry Seeley, a British scientist, divided the dinosaurs and named the two groups in 1887.
Fearsome giants such as Tyrannosaurus rex and Apatosaurus are both saurischians. Still, many plant-eating dinosaurs, including Triceratops and Stegosaurus, are classified as ornithischians—which means bird-hipped—because their pubis bone was initially thought to resemble birds.
Enough about the name. Ornithischians remain a fascinating and diverse dinosaur group. Below are ten impressive ornithischians you should know. Come and check them!
1. Hypsilophodon
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Hypsilophodon lived in the early Cretaceous period, about 125 to 120 million years ago in England, Portugal and North America.
Hypsilophodon was a herbivore (plant-eater), about 4 to 7 feet (1.2 to 2.1 meters) long.
About 20 perfect fossilized skeletons of Hypsilophodon have been found together in the Isle of Wight, England, so it seems likely that these animals must have lived and died together. Scientists, therefore, believe that Hypsilophodon lived in herds.
For almost a century, Hypsilophodon was thought to have been tree-dwelling, much like a modern tree-kangaroo. However, in the 1970s, the skeleton was reexamined, and most scientists now believe that there is no evidence that Hypsilophodon lived in the trees, it seems. Itore is likely that Hypsilophodon is a fast runner.
2. Triceratops
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In the 1880s, no one had ever seen a fossil from a horned dinosaur, so when paleontologist O.C. Marsh first examined Triceratops horn fragments, he was understandably puzzled. Marsh thought the fossil was from an ancestor of the American bison, so he named it Bison alicorns. Additional fossil discoveries provided more evidence, and in 1889 Marsh named the species Triceratops horridus.
Triceratops’ skull measures about 8 feet long—almost a third of its body length—yet it was much lighter than it looks. Inside its massive head, its brain was smaller than that of a German shepherd. And in its beak-shaped mouth, Triceratops had between 144 and 160 teeth, which it replaced completely two and four times over its lifetime.
3. Stegosaurus
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Lumbering Stegosaurus stenops adults measured about 25 feet long—about the length of four twin mattresses. This armored dinosaur likely used the distinctive plates along its back for display to attract mates or signal its species. Fossils of stegosaur plates are crisscrossed with grooves for blood vessels, indicating that they were covered with skin when the animal was alive.
The four flexible spikes on its tail, though, were used for defense against predators like the saurischian predator Allosaurus.
Unlike Triceratops, Stegosaurus had a remarkably tiny head. But both dinosaurs had surprisingly small brains relative to their overall body size. The brain of an adult Stegosaurus was only the size of a walnut—astonishing for an animal of its size. So astonishing that some biologists once thought it might have had two brains, but the second “brain” turned out to be an enlargement in the spinal cord.
4. Hadrosaurs
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Hadrosaurs also called hadrosaurids or duck-billed dinosaurs, are members of the ornithischian family Hadrosauridae. This group is known as the duck-billed dinosaurs for the flat duck-bill appearance of the bones in their snouts. The family, which includes ornithopods such as Edmontosaurus and Parasaurolophus, was a collaborative group of herbivores during the Late Cretaceous Period in Asia, Europe, Africa, Antarctica, South America, and North America. Hadrosaurids are descendants of the Upper Jurassic/Lower Cretaceous iguanodontian dinosaurs and had a similar body layout.
5. Parasaurolophus
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This animal is a genus of hadrosaurid (sometimes referred to as the hadrosaurs or duck-billed dinosaurs) from approximately 76.5–73 million years ago (late Cretaceous). It is a herd animal feeding on the park’s rich vegetation. The most stunning feature of the Parasaurolophus is the crest on its head. So it’s also on the list of 10 Dinosaurs with Head Crests That are Fun to Learn About.
Some believed it was a snorkel for when the animal was in the water; others felt it was used in combat. We now know that it serves for display and communication, allowing the animals to remain in contact over distance by amplifying their loud criesranches.
6. Ankylosaurus
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Ankylosaurus was a massive herbivore (plant-eater) that lived in the late Cretaceous period (74 to 65 million years ago) in the North. It was one of the dinosaurs that died out in the Cretaceous-Tertiary extinction 65 million years ago.
Ankylosaurus was covered with massive armor to protect it from predators, was up to 33 feet (10 meters) long, and weighed over 4 tons.
The armor consisted of hundreds of oval-shaped bony plates embedded in its leathery hide. There were also four spikes on its head (two at the back and one on each cheek) and a heavy bony growth on the end of its tail, which was probably used as a club in defense when Predators attacked ankylosaurus.
Ankylosaurus was named by Barnum Brown in 1908 and meant “stiffened lizard.
7. Pisanosaurus
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Pisanosaurus is an early (currently the earliest known) Ornithischian dinosaur. It lived during the Triassic period, between about 228 and 216 million years ago, in Argentina.
Pisanosaurus was only about 3 feet (1 meter) long and weighed perhaps around 10 to 20 pounds (4.5 to 9 kilograms). It was a herbivore (ate plants) and walked bipedally.
Only one species (Pisanosaurusmertii) of Pisanosaurus is currently known, and even this is only known from a single incomplete fossilized skeleton.
Pisanosaurus lived in Argentina around the same time as the carnivorous dinosaur Herrerasaurus, and it has been suggested that Herrerasaurus may have preyed upon Pisanosaurus.
8. Sinoceratops
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Sinoceratops is a genus of ceratopsians that lived in China during the Late Cretaceous, living about 72-66 million years ago. It lived alongside Shantungosaurus, Zhuchengtyrannus, and Zhuchengceratops.
Like most centrosaurs, Sinoceratops had a single nasal horn and no horns above its eyebrows. However, what distinguishes this ceratopsian is its frill pattern, a series of forward-curving frill horns that run around the top of the frill. There is also a series of low-set knobs on the top of the frill, which is not seen in any other known ceratopsian.
9. Homalocephale
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Homalocephale is an extinct genus of pachycephalosaurid dinosaurs that lived during the Late Cretaceous period. Its name means “even head” and was noted for its wide hips and flat skull. Homalocephale’s distinctive appearance was due to its thick flat skull. Paleontologists think that would most likely have helped to protect it from predators.
10. Kosmoceratops
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Kosmoceratops is a genus of herbivorous chasmosaurine ceratopsian dinosaurs, which lived during the Late Cretaceous period (late Campanian) in the island continent Laramidia that is now Utah, United States.
Kosmoceratops is distinguished by an ornate skull, the most ornate of any known dinosaur. The horns above the eyes are long, thin, and pointed. They project laterally from the head and curve downward. The orientation of these horns differs from most other ceratopsians, in which the horns are oriented either forward or backward.
There is a forehead-like hump on the skull roof in front of the eye sockets. The nasal horncore, the bony projection from which the nose horn grew, is flattened and blade-like. The frill of Kosmoceratops is the shortest relative to the width of any ceratopsian; it is about twice as wide as it is long.
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There you have it, ten Ornithischian Dinosaurs. Several other Ornithischian dinosaurs walked the earth’s surface, and as such, this list is not comprehensive.
By the way, do well to check out our animatronic dinosaurs. We have them for different dinosaurs, including beautiful ornithischiansand Saurischians.
