First reports of Crocodylopodus from East Asia: implications for the paleoecology of the Lower Cretaceous

Abstract

The distinctive crocodylian ichnogenus Crocodylopodus, previously reported only from a few Jurassic and lowermost Cretaceous sites in Europe, Central Asia and North Africa, occurs abundantly at several sites in the Cretaceous (?Aptian) Jinju Formation of Korea. It is therefore the first report of the ichnogenus from East Asia. Comparison between known crocodylian ichnogenera show that Crocodylopodus and Batrachopus, the latter predominantly known from the Lower Jurassic, represent small trackmakers that left narrow walking trackways with no tail traces, mostly in fine-grained emergent, lacustrine shoreline facies. In contrast the large crocodylian ichnogenus Hatcherichnus represents swimming behavior of large animals in siliciclastic fluvial, coastal plain settings, particularly in North America, where they represent a swim track ichnofacies. Such contrast between large aquatic crocodylian tracks, which remain very rare in the Cretaceous of Asia, and small Crocodylopodus spoor, show that the Korean occurrences represent a different paleoecology characterized by diverse, mostly small lake basin tetrapods.