The evolution of hermit crabs (Crustacea, Decapoda, Anomura, Paguroidea) on the basis of carapace morphology: a state-of-the-art-report

In our ongoing studies of both extinct and extant hermit crabs (Paguroidea Latreille, 1802), we have observed recorded a number morphological changes that taken place between Early Jurassic times (c. 185 million years ago) the present day. Species compositions paguroid assemblages from marine Upper Lower Cretaceous rocks in Europe are here compared with those modern settings. Basal paguroids cylindrical carapaces predominated reefal environments during Late Jurassic, but were gradually replaced by non-cylindrical carapaces. The most basal reveal branchial groove, condensation towards single (i.e., cervical) groove is shown to occurred early their evolutionary history. several extant, genera remnants combination other features, can be seen. For this reason, these considered primitive members amongst paguroids. study, resurrect family Probeebeidae erect new family, Paguropsidae n. fam, accommodate such as Paguropsis Henderson, 1888, Eopaguropsis Fraaije, Krzemi?ski, Van Bakel, Krzemi?ska & Jagt, 2012 Paguropsina Lemaitre, Rahayu Komai, 2018. Described also one pair (Pliensbachian) two pairs Middle (Callovian) isochelous chelae, all collected recently. A specimen Schobertella reveals some important traits shield had not been previously. earliest known example date clearly heterochelous chelae fossil record originates upper Kimmeridgian/Tithonian strata Boulonnais (northwestern France). first time, phylogenetic scheme Paguroidea, based on data carapaces, presented.