Robert E. Howard’s greatest use of a prehistoric beast was the “dragon” used in the first third of the novella “Red Nails.”

First, Howard’s description:

Through the thicket was thrust a head of nightmare and lunacy. Grinning jaws bared rows of dripping yellow tusks; above the yawning mouth wrinkled a saurian-like snout. Huge eyes, like those of a python a thousand times magnified, stared unwinkingly at the petrified humans clinging to the rock above it. Blood smeared the scaly, flabby lips and dripped from the huge mouth.

The head, bigger than that of a crocodile, was further extended on a long scaled neck on which stood up rows of serrated spikes, and after it, crushing down the briars and saplings, waddled the body of a titan, a gigantic, barrel-bellied torso on absurdly short legs. The whitish belly almost raked the ground, while the serrated backbone rose higher than Conan could have reached on tiptoe. A long spiked tail, like that of a gargantuan scorpion, trailed out behind.

The two iconic descriptions by artist are the Vincent Napoli illo from Weird Tales and the Barry Smith version from the Marvel funny book.

Here is a list of possibilities of what it could be:

Stegosaur: The big torso, short legs, and spiked tail makes the case in the positive. Stegosauroids did not have tusks and were plant eaters. Stegosauroids did not have long necks. Edgar Rice Burroughs had carnivorous Triceratops in the land of Pul-Ul-don in Tarzan the Terrible. Kentrosaurus was from Africa and different looking from your typical Stegosaurus. Would a zombie stegosaurus be a meat eater?

Dimetrodon: A pelycosaur from the early Permian Period, not a dinosaur but a synapsid. More related to mammals than dinosaurs. It does come closer with the short legs but lacking the long neck and spiked tail.

Spinosaurus: This was my pick for a long time. Just recently a tail was discovered and Spinosaurus is thought to have been a swimmer. A Theropod from the late Cretaceous in Africa. It does not have stubby legs and the spiked tail.

Archosaur: My obscure pick, specifically Arizonasaurus, an archosaur (pre-dinosaur) from the middle Triassic. It comes close to Howard’s description. Some illustrations even have a (small) spiny tail.

Panzer-Croc: First read about these in Bakker’s The Dinosaur Heresies. The true name is Pristichampsus, a galloping crocodile from the Eocene.

One last entry: Franken-dinosaur. The dragon(s) could have been made out of parts. Head of a meat eating therapod like an Allosaurus put on the body of a Stegosaurus.

Robert E. Howard made the dragon front and center and not window dressing as all to often happens. He knew what he was doing.