Bivalve bioerosion in Cretaceous-Neogene amber around the globe, with implications for the ichnogenera Teredolites and Apectoichnus

Amber samples with bivalve borings from six localities around the world, ranging in age from Hauterivian to Miocene, have been studied. The possible assignment to Teredolites or Gastrochaenolites is discussed considering the type of substrate as an ichnotaxobase. It is proposed to regard amber or similar resins as a variant of xylic substrates and to maintain the separation between the two ichnogenera and their different paleoecological implications. The amber borings are assigned to Teredolites clavatus Leymerie, 1842 and Apectoichnus longissimus (Kelly and Bromley, 1984), respectively. The presence of bioglyphs in a few borings suggests a mechanical production process, with pholadid bivalves such as Martesia preserved inside many of the samples representing the producer. In general, the amber-producing trees mostly grew along a forested coastline, where they were occasionally flooded by seawater or even transported from rivers into the sea and later deposited.