Footprints of Giant Birds from the Upper Eocene of the Paris Basin: An Ichnological Enigma

In 1859 the French geologist Jules Desnoyers reported the discovery of vertebrate footprints in the Late Eocene gypsum of the Paris region. Although they attracted some attention at the time, those footprints were never illustrated or described in detail, and the present whereabouts of the specimens seem to be unknown. Several types of footprints were referable to animals known by skeletal elements from the gypsum, but some were not. Among the latter were tridactyl footprints of very large birds, which Desnoyers tentatively attributed to the giant ground bird Gastornis, which had been discovered in the Lower Eocene of the Paris region a few years earlier. Gastornithids are now known from the Paleocene to the Middle Eocene, but no skeletal remains of giant birds have yet been found in the Upper Eocene of Europe. The tracks of giant birds from the gypsum of the Paris region are thus an example of fossil footprints without known osteological counterparts, and the identity of the trackmakers remains an enigma.