@ARTICLE{TreeBASE2Ref18148, author = {George D. F. Wilson and Gregory D. Edgecombe}, title = {The Triassic isopod Protamphisopus wianamattensis (Chilton) and comparison with extant taxa (Crustacea, phreatoicidea).}, year = {2003}, keywords = {}, doi = {}, url = {}, pmid = {}, journal = {Journal of Paleontology}, volume = {77}, number = {3}, pages = {454--470}, abstract = {Protamphisopus wianamattensis (Chilton, 1918) from the Middle Triassic (Anisian) Ashfield Shale in the Sydney Basin, Australia, is the earliest-known freshwater representative of the basal isopod suborder Phreatoicidea. In contrast, the late Paleozoic Palaeophreatoicidae species, which are morphologically distinct from extant families, are found in marine or estuarine facies. Comparison of _Protamphisopus wianamattensis_ with extant Phreatoicidea permits the external morphology of the fossils to be reconstructed and the species to be coded for cladistic analysis using a character set developed for living phreatoicideans. In the parsimonious trees as well as immediately suboptimal trees, _Protamphisopus_ is nested within clades related to the extant family Amphisopodidae. Although not included in the analysis, the Late Permian fossil _Protamphisopus reichelti_ Malzahn (in Glaessner and Malzahn, 1962) appears to be a member of the Palaeophreatoicidae, rather than placed among the living families. Therefore, a minimum age of Middle Triassic can be assigned to the basal branchings within the crown group of the Phreatoicidea. The minimum age for the colonisation of fresh water by the the suborder is also established although, given the advanced position of _Protamphisopus wianamattensis_ in the cladograms, the habitat shift may have occurred earlier. The biogeographic distribution of extant Phreatoicidea on fragments of Gondwana is consistent with Early Mesozoic origins for the major clades of this isopod suborder.} }

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