Thyreophorans are a group of ornithischian (bird-hipped) dinosaurs that include Scutellosaurus, Scelidosaurus, stegosaurs, and ankylosaurs. Thyreophorans were quadrupedal plant-eaters that had bony body armor (plates, spikes, and/or scutes).

These plant-eaters include the stegosaurs (plated dinosaurs like Stegosaurus, Kentrosaurus, etc.) and the ankylosaurs (armored dinosaurs like Ankylosaurus, Euoplocephalus, etc.).

Kentrosaurus:

Kentrosaurus measured up to 17 feet long (5 m) and weighed about 2 tons, but its small brain was the size of a walnut. Its skull was long and narrow, with a toothless beak and small cheek teeth. Its head was carried close to the ground. It had hoof-like claws on its toes.Kentrosaurus had two rows of bony plates that were embedded in its back that went from its neck to its mid-section. A double row of spikes ran from its mid-section to its tail, and a pair spikes protected its shoulders. Since these were not attached to its bones, no one is sure exactly how they were positioned. Also, the function of the plates is uncertain; perhaps they were for temperature regulation, since they contained networks of blood vessels, or maybe they were for protection or mating display purposes. The spikes were used as protection from predators.Kentrosaurus had a very small, but long, brain. The olfactory bulbs were well developed; this is the part of the brain that gave the animal a very good sense of smell.Kentrosaurus lived during the late Jurassic Period, about 156 to 150 million years ago.Kentrosaurus, like other Stegosaurians, may have been a herding animal. This plated dinosaur was an ate low-lying plants. It must have eaten a large amount of low-calorie plant material each day to sustain itself.

Ankylosaurus:

Ankylosaurus was a huge armored dinosaur, measuring about 25-35 feet (7.5-10.7 m) long, 6 feet (1.8 m) wide and 4 feet (1.2 m) tall; it weighed roughly 3-4 tons.Its entire top side was heavily protected from carnivores with thick, oval plates embedded (fused) in its leathery skin, 2 rows of spikes along its body, large horns that projected from the back of the head, and a club-like tail. It even had bony plates as protection for its eyes. Only its under-belly was unplated. Flipping it over was the only way to wound it.Ankylosaurus had four short legs (the rear legs were larger than the front legs), a short neck, and a wide skull with a tiny brain.Ankylosaurus was the last of the ankylosaurids (armored dinosaurs) to evolve, and the biggest. It lived in the late Cretaceous Period, about 70-65 million years ago. Ankylosaurus and all the other dinosaurs (except birds) perished in the Cretaceous-Tertiary extinction, 65 million years ago.

Euoplocephalus:

Euoplocephalus was a large armored dinosaur, measuring about 20 feet (6 m) long; it weighed about 2 tons. Its wide head had a horny, toothless beak, small, peg-like cheek teeth, bony horns, and a small brain.Its entire top side was heavily protected from carnivores with thick, oval plates embedded (fused) in its leathery skin, rows of large spikes along its body, large horns that projected from the back of the head, and a raised, club-like tail. It even had bony plates as protection for its eyes and a pair of big spines on the sides of its head. Only its under-belly was unplated. Flipping it over was the only way to wound it.Euoplocephalus had four short, sturdy legs and a short neck.Euoplocephalus may have traveled in herds.Euoplocephalus lived during the late Cretaceous period, about 70-65 million years ago. Euoplocephalus and all the other dinosaurs (except birds) perished in the Cretaceous-Tertiary extinction, 65 million years ago.Among its contemporaries were the large meat-eating Tyrannosaurus, Tarbosaurus, and Deinonychus. Short of being flipped over, Euoplocephalus was well protected from these predators, and could even defend itself with its club-like tail.

Nodosaurus:

Nodosaurus was a large, armored, quadrupedal , tank-like dinosaur.Nodosaurus lived during the early Cretaceous period, about 113-98 million years ago. Nodosaurus was an herbivore (a plant-eater). It ate low-lying plants, like ferns and cycads, with its leaf-shaped teeth.This nodosaurid (with no tail club) ankylosaur was about 13 to 20 ft (4-6 m) long. It was an ornithischian (bird-hipped) dinosaur with bony dermal plates covering the top of its body. It had four short legs, five-toed feet, a short neck, and a long, club less tail. The narrow head had a pointed snout and powerful jaws. It may have had spikes along its sides, but only incomplete fossils have been found, so this is not certain.Nodosaurus means "knobby or node lizard." It was named by paleontologist Othniel C. Marsh in 1889. The type species is N. textilis.Three very incomplete Nodosaurus fossils have been found in Wyoming and Kansas; no skulls have been found yet.

Panoplosaurus:

Panoplosaurus was an armored, tank-like dinosaur that lived during the late Cretaceous period, about 76-73 million years ago. No one knows what color the dinosaurs were.Panoplosaurus was an herbivore (a plant-eater). It ate low-lying plants, like ferns and cycads. This nodosaurid ankylosaur (with no tail club) was about 23 ft (7 m) long and weighed about 3.5 tons. This ornithischian dinosaur had a bulky body, four short legs, a short neck, and a stiff tail.

Polacanthus:

Polacanthus was an armored, spiked, plant-eating dinosaur from the early Cretaceous period, from about 132 to 100 million years ago. Polacanthus means "many spines." Some paleontologists think that Polacanthus is the same genus as Hylaeosaurus.Polacanthus was about 12 feet (4 m) long and about 4.8 feet (1.5 m) tall. It was a bulky quadruped that relied on its many rows of bony spikes for protection.Polacanthus was an herbivore, a plant-eater. Fossils of this ankylosaurid have been found in England.

Sauropelta:

Sauropelta was an armored dinosaur from the early Cretaceous period. It looked a lot like its more advanced relative Ankylosaurus, but didn't have the bony nodes at the end of its tail or horns on its head.It was about 25 feet (7.6 m) long and weighed over 3 tons. It had a narrow skull with massive jaws, small, leaf-shaped cheek teeth and a toothless horny beak. It had horn-covered plates embedded in its skin all over its body (except on its underbelly). Its entire top side was heavily protected from carnivores. Only its under-belly was unplated. Flipping it over was the only way to wound it.Sauropelta lived during the early Cretaceous Period, about 116-91 million years ago. This huge, heavy reptile was an herbivore (it ate only plants). It had to eat a huge amount of low-lying plant material to sustain itself so its gut must have been very large. It probably had a fermentation compartment to aid in the digestion of the tough plant material, producing prodigious amounts of gas.