Every day hundreds of tourists take pictures of the “Duomo,” the Milan gothic cathedral. But very few of them notice a curious creature, depicted in the bas relief that surrounds the main gate of the church.

While the body looks distinctly dog like, the creature has a long neck, a dinosaur-like head, and webbed feet. The city of Milan has strong historical links with dragons and the symbol of the city is the “biscione” or "great snake."

However in this image, unlike the fierce “biscione” which is depicted as a fierce monster chomping a little boy in its jaws, this dinosaur-dog-dragon has a friendly look and is seemingly depicted eating a leaf.

Built over five centuries between 1386 and 1805, it is unclear exactly when this strange creature was added (likely much later in the process) or why the carver did so. Whether it was a flight of fancy like the gargoyles that decorate the church, had specific symbolism that is now lost, or was the attempt to represent some real creature remains a mystery.

Looking closely at the bas relief, the "dinosaur" looks small, almost puppy-like. One explanation is that the scene depicts the birth of Tarantasio, a mythical creature that appeared in a swamp south of Milan in the 12th century after a series of devastating floods. The "dinosaur" mysteriously disappeared two hundred years later on December 31, 1299. Later, a large bone floated to the surface of the swamp after a night of heavy rains.