Solution to a 300-year-old zoological mystery: the case of Thomas Bartholin's merman

Abstract

In 1654 Dutch anatomist Thomas Bartholin published an illustration of a skeletal forelimb and a rib from an animal that had been caught off the coast of Brazil. Bartholin identified the specimen as a merman. Subsequent authors have hypothesized that it was a human with sirenomelia (fused legs). However, it is now acknowledged that mer-people are mythical and the drawing of the specimen does not match expected morphology for a human with sirenomelia. Until now, therefore, the correct identity of the specimen has remained unknown. Bartholin gave details on the specimen's size and added that before it was skeletonized the fingers were joined by a common membrane. We therefore compared Bartholin's illustration with the forelimb skeletons of west Atlantic marine animals of appropriate size in which the fingers are embedded in a flipper. The morphology of the specimen matches that of a manatee (Trichechus sp.) and is significantly different from that of the Caribbean monk seal (Monachus tropicalis) and from those of whales (Cetacea). The specimen was therefore a manatee, and a three-century-old zoological mystery is solved.