Excavations revealed the Ishtar Gate (pictured above) and carved on this was the mushush. To avoid confusion, I should remark that this creature's name was originally mis-read as sirrush, in which mistaken form it sometimes appears in books on cryptozoology.
As can be seen, the creature is somewhat stylized, but speculation has arisen as to whether it was based on some genuine animal known to the Babylonians. R. Koldeway, who excavated it in 1902, thought it might be a form of iguanodon which survived into historical times. Another suggestion is that reports of mokele-mbembe, the legendary African cryptid, somehow reached the Babylonians. There is no evidence, however, that Babylonian knowledge of Central Africa existed. Willy Ley suggested it was a surviving sivatherium, a kinsbeast of the giraffe and okapi. The identity of this beast, commonly called the Dragon of the Ishtar gate, is currently unknown. It does, however, have a horn on its nose. Could it be a depiction of a rhinoceros that had been sculpted by someone who had never actually seen a rhinoceros, but had heard a vague description? In such case it is more likely to be an Indian rhinoceros, as this has but a single horn.