Data from: Cretaceous amber inclusions illuminate the evolutionary origin of tardigrades

Supplementary files to the "Cretaceous amber inclusions illuminate
the evolutionary origin of tardigrades" paper which include All raw
files from the phylogenetic analysis (i.e., t, p, and tree files
fromMrBayes, output tree from ASTRAL and IQTree, mcmc files from MCMCTree,
and tre and log files from BEAST), RScripts used, and assembled
Actinarctus doryphorus genome. Tardigrades are a diverse phylum of
microscopic invertebrates widely known for their extreme survival
capabilities. Molecular clocks suggest that tardigrades diverged from
other panarthropods before the Cambrian, but their fossil record is
extremely sparse. Only the fossil tardigrades Milnesium
swolenskyi (Late Cretaceous) and Paradoryphoribius
chronocaribbeus (Miocene) have resolved taxonomic positions,
restricting the availability of calibration points for estimating for the
origin of this phylum. Here, we revise two crown-group tardigrades from
Canadian Cretaceous-aged amber using confocal fluorescence microscopy,
revealing critical morphological characters that resolve their taxonomic
positions. Formal morphological redescription of Beorn
leggi reveals that it features Hypsibius-type claws. We
also describe Aerobius dactylus gen. et sp. nov. based
on its unique combination of claw characters. Phylogenetic
analyses indicate that Beo. leggi and Aer.
dactylus belong to the eutardigrade superfamily Hypsibioidea,
adding a critical fossil calibration point to investigate tardigrade
origins. Our molecular clock estimates suggest an early Paleozoic
diversification of crown-group Tardigrada and highlight the importance
of Beo. leggi as a calibration point that directly impacts
estimates of shallow nodes. Our results suggest that independent
terrestrialization of eutardigrades and heterotardigrades occurred around
the end-Carboniferous and Lower Jurassic, respectively. These estimates
also provide minimum ages for convergent acquisition of cryptobiosis.