Serious monsters
We find Aldrovandi’s dragons in serious books about nature. They were pictured and discussed alongside real, existing animals. This mix of reality and fantasy was not unusual. There were still a lot of things people didn’t know about nature, and scholars still wanted to describe it in as much detail as possible: not just the species they’d actually seen, but the ones they’d only heard or read about as well.
This dragon is described, for instance, in Aldrovandi’s work on snakes and dragons, De serpentum et draconum historariae.
It wasn’t that Aldrovandi always believed in them himself, dragons were just part of the equation by default. They were simply a part of the way people experienced nature at the time.
Several of Aldrovandi’s books show all kinds of strange creatures, such as basilisks, sea unicorns, and mermaids. General conceptions as they prevailed in the 16th and partly in the 17th century, took into account the possibility that these creatures existed.