Compsognathus was only the size of a chicken! It is believed to have been one of the smallest-known dinosaurs. Compsognathus had two long and thin legs and feet with three toes each. The Compsognathus' head was small and pointed and it had small, but sharp teeth. The other distinguishing features of the Compsognathus include the hollow bone structure and a long and very flexible neck.

Compsognathus had short arms, both with two clawed fingers. Its long tail offered the dinosaur balance and stability during fast turns. Compsognathus or 'pretty jaw' was named in 1859, by Johann A. Wagner. The dinosaur was a carnivore that caught and ate smaller animals, insects and lizards. They fed on the lizard called Bavarisaurus that was known to be a very fast runner.

Compsognathus was between 28 inches and 4.6 feet long and stood 10 inches or 26 cm tall, at the hips. It weighed 6.5 pounds or 3 kg and lived about 155 million years ago. Fossils of Compsognathus have been discovered in Germany and France. They were light and fast-running predators that had large brains. They belonged to the super family of maniraptoriformes, which indicates that they were advanced coelurosaurs with fused wrist bones.