Palaeobiology of tanaidaceans (Crustacea: Peracarida) from Cretaceous ambers: extending the scarce fossil record of a diverse peracarid group

Abstract

International audienceDiverse assemblages of tanaidacean peracarid crustaceans from western Tethyan continental deposits suggest that the group was relatively common in or around ancient resin-producing forests. Here we report the results of an examination of 13 tanaidacean specimens from three Cretaceous (Albian to Turonian) French amber deposits. Two new species of the fossil family Alavatanaidae are placed in the previously described Early Cretaceous genus Eurotanais: Eurotanais pyrenaensis sp. nov. from Cenomanian Pyrenean amber (Fourtou, Aude) and Eurotanais seilacheri sp. nov. from Turonian Vendean amber (La Garnache, Vendée). The remaining specimens are placed in three newly erected genera and species (but family incertae sedis): Arcantitanais turpis gen. et sp. nov. from Albian–Cenomanian Charentese amber (Archingeay, Charente-Maritime), and Tytthotanais tenvis gen. et sp. nov. and Armadillopsis rara gen. et sp. nov. from Pyrenean amber. These are the first formally described fossils that might be related to the paratanaoidean families Nototanaidae and Paratanaidae, sharing with these some putatively derived features and providing possible evidence for the antiquity and morphological stability of these families and the suborder Tanaidomorpha. The distinctive features and character combinations of these fossil taxa are discussed in connection with possible relationships to the living lineages of tanaidaceans. Propagation phase-contrast X-ray synchrotron microtomography was used to obtain high-quality 3D images for some fossils. A discussion is provided on the putative palaeobiology of tanaidaceans and the French resiniferous forest ecosystem. The discovery of these new tanaidaceans extends the palaeogeographical distribution and stratigraphical range of the family Alavatanaidae and sheds new light on the palaeoecology and diversity of tanaidaceans in pre-angiospermous woodlands

Exceptionally preserved cryptoniscium larvae - morphological details of rare isopod crustaceans from French Cretaceous Vendean amber

“…However, only one crustacean species (Tanaidacea) has been recorded for Vendean amber Néraudeau et al, 2017). Yet, no parasite-host relationship between epicarideans and tanaidaceans has ever been recorded, and the tanaidaceans known from Vendean amber are too small to represent final hosts of epicarideans (Eurotanais seilacheri in Sánchez-García et al, 2016).…”

A fossil tanaidacean crustacean from the Middle Jurassic of southern Germany

“…The remaining Jurassic tanaidacean species have been placed in monotypic (genus-ranked) groups and can simply be referred to by their species names (without generic name) when discussing the possible affinity to the already described species (e.g., Lanham 1965). All other nonmonotypic tanaidacean groups that are only known from fossils are representatives of Tanaidomorpha (vonk & Schram 2007;Sánchez-garcía et al 2015Sánchez-garcía et al , 2016Sánchez-garcía et al , 2017hearD et al 2018).…”

“…1). Fifteen of these species are known from inclusions in amber of the Cretaceous and Neogene (vonk & Schram 2007;Sánchez-garcía et al 2015Sánchez-garcía et al , 2016Sánchez-garcía et al , 2017hearD et al 2018). The remaining fossils come from nonamber sites.…”

Marine microorganisms as amber inclusions: insights from coastal forests of New Caledonia

“…amphipods, Coleman, 2004; testate amoebae, Schmidt et al, 2010; diving beetles, Gómez and Damgaard, 2014). It has been shown that fresh resin flowing into limnetic waters may trap limnetic microorganisms such as algae and testate amoebae and even aquatic arthropods (Schmidt and Dilcher, 2007). Marine microorganisms occur sometimes as contaminants on the surface of, and in fissures reaching into, amber pieces, if the amber-bearing strata were exposed in the tidal zone or if amber was washed ashore after floating in seawater (e.g.…”