The Triassic Tetrapod Track Record: Ichnofaunas, Ichnofacies and Biochronology

Triassic tetrapod tracks have long been studied, including classic ichnofaunas such as those of the lower Newark Supergroup of eastern North America and the Bundsandstein of central Europe. They are known from all seven continents and encompass five archetypal vertebrate ichnofacies for nonmarine environments (Chelichnus, Grallator, Batrachichnus, Brontopodus, Characichnos), all of which are present in the Triassic: (1) Chelichnus ichnofacies – Brasilichnium ichnocoenosis; (2) Grallator ichnofacies – Grallator ichnocoenosis; (3) Batrachichnus ichnofacies – Chirotherium and Apatopus ichnocoenoses; (4) Brontopodus ichnofacies – Dicynodontipus, Therapsipus, Brachychirotherium and Evazoum ichnocoenoses; and (5) Characichnos ichnofacies – unnamed ichnocoenosis. There are five temporal subdivisions of the Triassic that can be recognized based on tetrapod tracks: (1) earliest Triassic – dicynodont tracks; (2) Early-Middle Triassic (Olenekian-early Anisian) – chirothere(archosaur-) dominated assemblage; (3) late Middle Triassic (late Anisian-Ladinian) – dinosauromorph assemblage; (4) early Late Triassic (Carnian-early Norian) – tridactyl dinosaur assemblage; and (5) late Norian-Rhaetian – sauropodomorph track assemblage.