When designing King Kong, Cooper wanted him to be a nightmarish gorilla monster. As he described Kong in a 1930 memo, "His hands and feet have the size and strength of steam shovels; his girth is that of a steam boiler. This is a monster with the strength of a hundred men. But more terrifying is the head—a nightmare head with bloodshot eyes and jagged teeth set under a thick mat of hair, a face half-beast half-human". Willis O'Brien created an oil painting depicting the giant gorilla menacing a jungle heroine and hunter for Cooper. However, when it came time for O'Brien and Marcel Delgado to sculpt the animation model, Cooper decided to backpedal on the half-human look for the creature and became adamant that Kong be a gorilla. O'Brien on the other hand, wanted him to be almost human-like to gain audience empathy, and told Delgado to "make that ape almost human". Cooper laughed at the end result, saying that it looked like a cross between a monkey and a man with very long hair. For the second model, O'Brien again asked Delgado to add human features but to tone it down somewhat. The end result (which was rejected) was described as looking like a missing link. Disappointed, Cooper stated, "I want Kong to be the fiercest, most brutal, monstrous damned thing that has ever been seen!" On December 22, 1931, Cooper got the dimensions of a bull gorilla from the American Museum of Natural History telling O'Brien, "Now that's what I want!" When the final model was created, it had the basic look of a gorilla but managed to retain some human-like qualities. For example, Delgado streamlined the body by removing the distinctive paunch and rump of a gorilla. O'Brien would incorporate some characteristics and nuances of an earlier creature he had created in 1915 for the silent short "The Dinosaur and the Missing Link" into the general look and personality of Kong, even going as far as to refer to the creature as "Kong's ancestor". When it came time to film, Cooper agreed that Kong should walk upright at times (mostly in the New York sequences) in order to appear more intimidating.