Internal anatomy of a brachyuran crab from a Late Cretaceous methane seep and an overview of internal soft tissues in fossil decapod crustaceans

Cretaceous-aged methane seep carbonates in the Western Interior Seaway, USA, have yielded a relatively high diversity and concentration of fossils, including decapod crustaceans, compared to their surrounding, contemporaneous sediments. With technological advances in non-destructive imaging techniques, the internal anatomy of decapods can be studied in remarkable detail. Here, we present a brachyuran crab specimen from an upper Campanian methane seep carbonate in South Dakota, USA. While the external morphology of the crab is insufficient for species identification ( Secretanella sp.), remarkable details of the internal morphology are preserved including soft tissues. Four phyllobranchiate gills are visible due