Substrate-independent feeding mode of the ichnogenus Phymatoderma from the Lower Jurassic shelf-sea deposits of central and western Europe

Deposit-feeding strategies recorded in the ichnogenus Phymatoderma from the Lower Jurassic shelf-sea deposits in central (Dotternhausen, southwest Germany) and western Europe (Asturias, north Spain) are revealed by geochemical and microscopic analyses. Thin-section observations showed that the trace-maker of Phymatoderma from Asturias ingested bioclastic skeletal sediments, and that from Dotternhausen ingested fine-grained siliciclastic sediments. Geochemical analysis elucidated that the trace-makers of Phymatoderma from both Asturias and Dotternhausen were non-selective deposit feeders (i.e., indiscriminately ingesting sediment particles on the seafloor), although the ingested sediments were significantly different in lithology. Microscopic analysis revealed that the Early Jurassic Phymatoderma-producers mainly fed on calcareous nannoplankton, i.e., coccolithophores, dinoflagellates, as well as their phytodetritus. Here, we demonstrate a substrate-independent feeding mode in the Early Jurassic Phymatoderma-producers, which accords with the similar morphologic, paleogeographic, and chronologic context of Phymatoderma from Asturias and Dotternhausen.