DID VERTEBRATES MAKE THE TRAILS KOUPHICHNIUM (JURASSIC) AND MICRICHNUS (TRIASSIC)?
BY KENNETH E. CASTER
Heteropodous trails from the Mesozoic rocks of Europe and North America which have been consistently attributed to vertebrates appear, upon detailed study in the light of modern invertebrate ichnology, to have been made by horseshoe crabs. Kouphichnium of the Jurassic lithographic limestone of Bavaria has been assigned since its original description (1862) to a variety of diminutive vertebrates: pro-avian, Archeopteryx, pterodactyl, mammal, and dinosaur (Ornitholestes). A bipedal vertebrate has been required to explain the heteropody. Limuloid trails, as the writer showed in 1938, are heteropodous and of similar dimensions. Possibly the fact that the trail has been consistently interpreted in what now appears to be a reversed direction of walking has tended to obscure the problem. Micrichnus trails of the Triassic red beds of eastern United States are similar to Kouphichnium and have likewise been attributed . . .