Compsognathus was portrayed as a small chicken-sized dinosaur. It was green in color having multiple shades with dark striping across their back some also seem to have shades of red and blue as well and have a yellow underbelly. Compsognathus is significantly smaller in the movie than it was in real life. It was based on the type specimen from Germany, which was only 89 cm (35 in) long. A larger fossil, of 125 cm (49 in) long, was discovered in France. The French specimen is probably an adult, while the German specimen is an infant.
Dr. Robert Burke misidentified it as "Compsognathus triassicus" instead of "Compsognathus longipes". The scriptwriters confused it with Procompsognathus (from The Lost World novel) of which triassicus is a species.
Compsognathus has a creative attack tactic for their small size. The alpha appears first and confronts the victim, who is surrounded by the other Compys before he/she knows they are coming. While the prey is interacting with the Alpha, or ignoring it, the others will eventually spring and attack the victim, usually overwhelming it. For instance, Dieter Stark discovered the alpha, then attempted to bring it down, but many others came by, all around him, then attacked him many times before finally killing him. However, there is currently no evidence that Compsognathus hunted in packs, due a shortage of specimens.