The earliest true Spirorbinae from the late Bathonian and Callovian (Middle Jurassic) of France, Israel and Madagascar

Two new spirorbin species, Neomicrorbis israelicus sp. nov. and Spirorbis? hagadolensis sp. nov., are here described from the Callovian of Israel, together with two new variations of Neomicrorbis israelicus from the late Bathonian of northern France and Callovian of Madagascar. These are the geologically earliest true Spirorbinae. Our new data, and a literature review of microconchids and early spirorbins, suggest that the ecological switchover from spirorbiform microconchids to spirorbin polychaetes took place in the late Bathonian, and that the spread of spirorbins across the Jurassic and Early Cretaceous seas was rapid. The ecospace of spirally coiled spirorbiform microconchids could thus have been competitively taken over by true spirorbins. The true spirorbin polychaetes may have been ecologically more successful than their Paleozoic analogues – the microconchids. The general rarity of spirorbin-bearing localities in Europe from the Bathonian to Albian supports the hypothesis that the Spirorbinae likely originated in the equatorial Tethys and only occasionally spread to the northern hemisphere seas until the end of the Early Cretaceous. Spirorbins finally became common, diverse and widespread in the northern seas by the Late Cretaceous, and even more so in the Cenozoic.