He speaks with a British accent.
He is a pterosaur, a flying reptile contemporary to the dinosaurs but only distantly related to them. His kind was present on the Late Cretaceous between 75 and 65 million years ago and was one of the species that saw the Cretaceous-Tertiary, K-T, K-Pg or Cretaceous-Paleogene extinction, which wiped out not only his kind but 75% of all species on Earth.
Despite being mostly evil and wicked, he does have an honorable side as well . He once helped the Dinosaucers to retrieve a bunch of Pteranodon eggs and take them to Reptilon, where they would grow and develop appropriately, instead of giving them to Genghis Rex who would raise them to join the Tyrannos. Terrible Dactyl even takes one of the baby pteranodons there himself. Even Genghis Rex respects this decision, as he does not punish his comrade. Instead, Rex seems to feel that this protective instinct Terrible Dactyl has for his sister species is instinctive and cannot be removed or suppressed.
- In the German dub of Dinosaucers (Die Astro Dinos) Terrible Dactyl's name was dubbed as "Dactylo"