New late Paleozoic conchostracan (Crustacea: Branchiopoda) from the Shackleton Glacier Area, Antarctica: Age and paleoenvironmental implications

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Abstract
Lake deposits of the Pagoda Formation (Upper Carboniferous?-Lower Permian) at Mt. Butters, Shackleton Glacier area, central Transantarctic Mountains, Antarctica, yield a low diversity biota including a new species of conchostracan, Cyzicus (Lioestheria) shackletonensis. Locally, conchostracans occur in large numbers near the tops of thin coarsening-upward cycles in siliciclastic sediments. Regionally, the Pagoda Formation consists of glacigenic deposits of the Gondwanide ice sheet that covered much of the land in southern high latitudes. At Mt. Butters, the lake deposits document the presence of an ice-margin lake in front of the advancing ice sheet. Deposition from suspension within the lake was interrupted by introduction of sand and silt deposited in the conchostracan-bearing, upward-coarsening sequences. Conchostracans of the Pagoda Formation are associated with other arthropods (euthycarcinoids and ostracodes), and wood fragments; burrows produced by small animals moving just beneath the sediment surface are abundant in some horizons. Few conchostracan occurrences are known from the Carboniferous-Permian of Antarctica; this is the second recorded occurrence, and it increases the number of described species to three.