CRETACEOUS POLAR ARTHROPODS ON WALKABOUTS: NEWLY DISCOVERED ARTHROPOD TRACE FOSSILS FROM THE WONTHAGGI FORMATION (BARREMIAN), VICTORIA, AUSTRALIA
Thus we are pleased to report the discovery of multiple arthropod trackways in fine-grained fluvial-floodplain sandstones from the Wonthaggi Formation (Barremian) near Inverloch, Victoria. Two distinctive types of trackways are evident, with track series and sets that allow for preliminary classification of their tracemakers. Type 1 is represented by 16-18 mm wide and straight to meandering trackways, each with 3 tracks/series and 6 tracks/set; trackway lengths vary from 12-49 cm long (n=7). Type 2 trackway consists of a single specimen, ~5 cm wide and 30 cm long, with at least 3 tracks/series and parallel linear impressions within the trackway. We propose the Type 1 trackways were made by insects, whereas the Type 2 trackway may have been from a crayfish. These arthropod trackways are the first reported from the Cretaceous of Victoria, and among the few from Cretaceous polar environments. Such trackways also likely represent seasonal behaviors, with insects and crayfish walking on emergent surfaces after overwintering, spring thaws, and flooding. These trace fossils thus help give tantalizing insights on arthropod adaptations to these extreme environments during the Cretaceous.