Tetrapod and large burrows of uncertain origin in Triassic high paleolatitude floodplain deposits, Antarctica

True types of large diameter burrows, recognized by non-overlapping size di stributions. occur in, high paleolatitude floodplain, deposits of the Lower Triassic Fremouw Formation, Shackleton Glacier area, Antarctica Type G (gi ant) burrows are gently dipping tunnels 8 to 19 cm in diameter. Type L (lar ge) burrows are 2 to 6.5 cm in. diameter, curved or subhorizontal tunnels t hat rarely branch; scratch markings on both burrow types generally are para llel or tangential to the long axis of the burrows. Type G burrows are interpreted as produced by tetrapods based on. similarit y in size, architecture, and surface markings to Permian burrows from South Africa that contain. complete skeletons of therapsids. These are the first tetrapod burrows described from Antarctica. Type L burrows have characteri stics of both fossil tetrapod and crayfish burrows, precluding identificati on. of an unique producer. Triassic tetrapods, including therapsids, that Lived in. high southern lati tudes probably burrowed to dampen the effects of seasonal environmental flu ctuations, just as do many of their mammalian counterparts living today in high latitudes. The paleolatitudinal and paleooclimatic distributions of bo rrowing therapsids and their mammalian descendents can be assessed by focus ing search efforts on very large burrows, and by identifying producers usin g criteria delineated herein; this will clarify the extent to which the bur rowing habit originated and persisted in. high Latitudes.