Dinosaur tracks and other archosaur footprints from the Triassic of South Wales

Abstract

Dinosaur tracks and other archosaur footprints from multiple stratigraphic levels in coastal exposures near Cardiff, and a site near Nottage, Porthcawl area, provide evidence of a diverse assemblage of trackmakers from the “marginal faciès”; of the Mercia Mudstone Group (Late Triassic), that can be closely compared with other Pangaean ichnofaunas of the same age.

The footprints, comprising at least 88 identified trackways from about 10 stratigraphie levels, can be assigned to the ichnogenera Grallator (Grallator), Grallator (cf. Anchisauripus), Chirotherium? or cf. Tetrasauropus, Pseudotetrasauropus? and Otozoum, most of which are new records for the Late Triassic of Great Britain. The ichnofauna indicates a relatively abundant and diverse archosaur‐dominated terrestrial vertebrate fauna in a semi‐arid setting subject to intermittent deposition by ephemeral streams. The numerically dominant track‐makers appear to have been small theropods with a lesser number of larger prosauropods and other archosaurs of uncertain affinity. Biomass estimates however, suggest that predators (the theropods) made up a minority of the fauna.

The track assemblages (ichnocoenoses) are inferred to be late Norian to Rhaetian in age, and are very similar to assemblages of comparable age from Colorado and Utah. Similar track assemblages are also known from eastern North America, Italy and southern Africa, presumably indicating the cosmopolitan nature of vertebrate ichnofaunas at this stage in the development of the supercontinent Pangaea.

At least two of the small theropods produced trackways indicative of running at estimated speeds of about 22 km/hour.

Key words:

• Norian and Rhaetian Tracks
• Grallator
• Running Theropods
• Pangaean Ichnofaunas

Notes

Corresponding author.