Terrestrial Isopods from Spanish Amber (Crustacea: Oniscidea): Insights into the Cretaceous Soil Biota

Terrestrial isopods (Crustacea: Oniscidea) are a model group for studying the colonization of land. However, their fossil record is remarkably scarce and restricted to amber inclusions, therefore deposits represent valuable windows past diversity morphology. Here we present new collection 11 terrestrial isopod specimens preserved in Albian-aged from Peñacerrada I outcrop, northern Spain, which collectively most thoroughly documented fauna Mesozoic Oniscidea. The three genera species identified belong five major groups Oniscidea: Eoligiiscus tarraconensis, genus (Ligiidae), Autrigoniscus resinicola, (Synocheta: Trichoniscidae), Heraclitus helenae, (Crinocheta: Detonidae?). These taxa significantly expand known Oniscidea demonstrate that considerable cladogenesis had already transpired by Albian. assemblage represents earliest-known diversification Oniscidea, extending direct evidence terrestrialization back late Early Cretaceous. exhibit some characteristics may inform hypotheses relating general patterns evolution. A discussion provided about different aspects paleoecology biology fossils compared Recent fauna. indicate Cretaceous were adaptive diversity, exhibiting innovations analogous what would 105 million years later.