Between the years 1551 and 1558, Conrad Gessner, a Swiss physician and naturalist, released his monumental five-volume work, Historiae animalium. Spanning 4,500 pages, it became the most widely circulated natural history encyclopedia of its era. Gessner aimed to categorize every known creature by synthesizing the writings of ancient scholars like Aristotle and Pliny with contemporary reports from explorers. His volumes included both real animals and creatures now recognized as purely mythical. While Gessner often vouched for the credibility of his sources, he was occasionally skeptical; for instance, he famously questioned the anatomical logic of a multi-headed hydra.

The true legacy of Historiae animalium lies in its extensive use of woodcut illustrations. Because artists often had to rely on second-hand verbal descriptions—a process likened to a visual game of "telephone"—the results varied from remarkably accurate to unintentionally comedic. Here is a look at several interpretations of the animal kingdom as seen through a 16th-century lens.

Land Mammals and Mythical Beasts

The beaver depicted in Gessner’s work possesses terrifying, jagged teeth. While real beavers do have strong incisors used for felling trees, the illustration transforms them into a nightmare-inducing feature. Similarly, the porcupine—whose name translates from French as "thorny pig"—is shown with a sinister coat of quills that looks far more aggressive than the defensive armor found on the actual animal.

The collection also features a unicorn, a creature that has never existed but was first described by the Greek doctor Ctesias. Ctesias characterized the animal as a "wild ass" from India with a white body, a red head, and a multi-colored horn. Gessner's illustration leans toward this early description rather than the graceful white horse commonly imagined today. Other land animals include a wolf-like fox and a Bactrian camel that lacks its characteristic thick winter fur and prominent humps. The hedgehog, usually considered quite charming, appears in the woodcut as a grumpy, startled creature with needle-like spikes.

Giants of the Wild

The elephant in this collection is particularly memorable for its frightening facial features and a trunk that looks more like a muscular limb than a delicate tool. The giraffe is another curiosity; early Europeans referred to them as "camel-leopards," believing them to be a hybrid species. Gessner’s artists rendered their ossicones—the skin-covered cartilage on their heads—as sharp, traditional horns, likely based on descriptions of horned African animals.

The armadillo is portrayed with a mischievous expression, looking almost as if it has just successfully executed a prank. Meanwhile, the hippopotamus is drawn with a much slimmer physique than the massive, semi-aquatic mammals we know today. The illustration even depicts a hippo walking atop the water while engaged in a confrontation with a crocodile.

Birds, Reptiles, and Marine Life

The rooster illustration captures the bird in a state of high-intensity crowing that borders on the alarming. For the sea turtle, the artist included a mouthful of sharp teeth. In reality, these reptiles possess beaks and internal throat structures called papillae rather than true teeth. The ostrich portrait is relatively successful regarding its anatomy, though it fails to capture the bird's naturally dark plumage, and its beak appears somewhat oversized.

The crocodile in the text features prominent red eyes, bearing a closer resemblance to a modern-day skink than a large predatory reptile. Finally, the whales and sea monsters depicted would have made any 16th-century sailor fear the open ocean. These marine giants are shown with terrifying scales and fierce countenances, reflecting the ancient Greek belief that whales were genuine monsters of the deep. Even the lion, while recognizable, is given a mane so perfectly styled it appears far more groomed than any wild predator's coat.