If you search for the smallest dinosaur, you’ll get a hummingbird as result. This is because birds, which evolved from dinosaurs, are classified as dinosaurs. If you search for non-avian dinosaurs you’ll still see only birdlike dinosaurs in the results. You’ll find the link for our video with the 5 smallest known dinosaurs, including avian dinosaurs in the description. But today, we’re talking about the smallest dinosaurs from different groups, excluding birds.
Let's start with the smallest sauropods.
Sauropods are dinosaurs famous for their long neck, small head, and giant size. The biggest sauropod was supersaurus, with a length of up to 39 meters or 128 feet. But which one is the smallest?
A Paleontologist discovered the fossil remains of a sauropod in a museum in Germany. Only a shinbone and an ankle are known, and the museum first described the fossil as a plesiosaur. The paleontologist realized it must have been the bones of a dinosaur. Further research suggests that it was the fossil remains of a sauropod that lived 180 million years ago in Germany. They also discovered that the animal had a size of 3-4 meters, or about 10 feet, which is small for a sauropod. They named it Ohmdenosaurus, which means “Ohmden Lizard”, after the place of its discovery. Ohmdenosaurus is the smallest known sauropod.
The smallest theropod dinosaur.
Theropods are a group of dinosaurs characterized by hollow bones and three-toes and claws on each limb. Spinosaurus, Tyrannosaurus, and Velociraptor are part of this group. But they were quite big. Birds are part of this group as well, and the bee hummingbird, with a size of 5.5 centimeters, or 2.1 inches, is the smallest avian theropod.
Epidexipteryx hui is the smallest known non-avian theropod and had a length between 25 and 30 cm (or 10-12 inches). Its fossil is well-preserved. Epidexipteryx lived 164 million years ago in what’s now China. It was a carnivore with sharp teeth and had feathers but couldn’t fly, as it was missing the pennaceous feathers necessary for flying.
The smallest Ornithopod
Ornithopoda are a group of bipedal herbivore dinosaurs. Ornithopoda were the only non-avian dinosaurs able to chew their food and one of the most successful groups of herbivores during the Cretaceous period. The most famous member of this group is probably Parasaurolophus, a dinosaur known for the crest on its head, that lived 76 million years ago. While this dinosaur reached a length of 9.5 meters or 31 feet, “Gasparinisaura”, its ancestor that lived 83 million years ago in Argentina, had a length of only 1.7 meters, or 5.6 feet, making it the smallest known dinosaur of the Ornithopoda group.
The smallest Ceratopsia
Ceratopsia is a group of herbivore dinosaurs with a beak, a neck frill, and horns on their face. The name Ceratopsia comes from the greek and means “horned faces”. Its most famous member is the 9 meters or 29.5 feet long triceratops, which lived 66-68 million years ago in North America. Its smallest member? Yamaceratops. A dinosaur that lived 83-86 million years ago in Asia, with a length of 50 centimeters, or 1.6 feet.
The smallest pachycephalosaurs
The name “pachycephalosaurs” comes from Greek and means “thick-headed lizards”. This group includes bipedal dinosaurs, that were herbivores or omnivorous, with thick skulls. The most famous member of this group is probably “Pachycephalosaurus”, which lived 70-66 million years ago in North America, but with a length of 4.5 meters or 15 feet, not the smallest member. This award goes to “Wannanosaurus”, a dinosaur with a length of only 50 centimeters, or 1.6 feet. It lived 72-69 million years ago in China.
The smallest Thyreophora
The name Thyreophora comes from Greek and means “shield bearers”. Dinosaurs of this group are often referred to as armored dinosaurs because their bodies were covered with bony armor. The award for the most famous Thyreophoran goes likely to ankylosaurus or stegosaurus. But the smallest member of this group is “Tatisaurus”, a dinosaur that lived 183-199 million years ago in China. Not much is known about it, but its estimated length is 1.2 meters or 3.9 feet.