Trace Fossils on Oceanic Volcanic Islands of Macaronesia: Current State of Knowledge

Ichnological research on trace fossils from the volcanic islands of Macaronesia (North Atlantic) is reviewed in light of significant advances over the past two decades. These studies contribute to the interpretation of paleoenvironments and enhance our understanding of the biota preserved in Miocene–Holocene shallow marine and non-marine deposits across the Azores, Cape Verde, Canary, Madeira, and Salvagens archipelagos. Trace fossils provide evidence of organisms not always known from body fossils, or whose potential tracemakers are absent from the extant island fauna. They include sedimentary burrows, borings in hard substrates, and traces of plant–insect interactions. Some ichnotaxa are widespread and common (e.g., Bichordites monastiriensis, Dactyloidites ottoi, Macaronichnus segregatis, Ophiomorpha nodosa, Thalassinoides isp.), whereas others are rare. Several new ichnotaxa have also been described from the islands, including Alaichnus kabuverdiensis (cumulative trace of bivalve siphons), Centrichnus dentatus (attachment trace of verrucid barnacles), Diopatrichnus santamariaensis (polychaete tubes armored with shell debris), Ericichnus bromleyi and E. asgaardi (bioerosion grooves of regular echinoids), and Rebuffoichnus guanche (coleopteran pupation chambers). Despite these advances, ichnological research in Macaronesia remains uneven, with many topics still underexplored and significant gaps in the geographic and inventory record.