A ROWELLELLA (LINGULATA, BRACHIOPODA) NESTLER IN A TRYPANITES BORING FROM THE MIDDLE ORDOVICIAN OF ESTONIA: AN EARLY COLONIZER OF HARD SUBSTRATE BORINGS

A steinkern of an endoceratid nautiloid siphuncle contains a Trypanites sozialis boring with a lingulate brachiopod Rowellella sp. shell inside. The steinkern of this endoceratid formed during early lithification of the sediment on the seafloor. The lithified steinkern of this siphuncle was either initially partially exposed to the seawater or was exhumed and stayed exposed on the seafloor, where it was colonized by boring organisms. This bioerosion resulted in numerous Trypanites borings in the siphuncle. After the death or exit of the Trypanites trace maker, a vacant boring was colonized by a small lingulate nestler Rowellella sp. This lingulate was likely preadapted to life in hard substrate borings when it first found its way into borings in living substrates in the Late Ordovician. The increased availability of hard substrate borings, combined with the increased predation pressure due to the GOBE, enhanced the colonization of hard substrate borings by lingulate brachiopods.

Automated summary

A steinkern of an endoceratid nautiloid siphuncle contains a Trypanites sozialis boring with a lingulate brachiopod Rowellella sp. shell inside. The formation of the lithified steinkern might have occurred partly in the seawater or after exhumation, which allowed colonization by boring organisms. This bioerosion resulted in numerous Trypanites borings in the siphuncle. The vacant boring was later colonized by a small lingulate brachiopod, which was preadapted to life in hard substrate borings and benefited from increased availability and predation pressure during the Late Ordovician GOBE.