Faunal aggregation in the Early Triassic Karoo Basin: Earliest evidence of shelter-sharing behavior among tetrapods?

The first report of a multitaxon aggregation from the Early Triassic Lystrosaurus Assemblage Zone is presented here. The aggregation includes two vertebrates-the suricate-sized cynodont Galesaurus planiceps and a gecko-like procolophonoid Owenetta kitchingorum-and a diplopod millipede. The high degree of articulation of the skeletal remains and the preservation of delicate bones in situ suggest that the animals were either rapidly buried or died in a place protected from weathering and agents of dispersal. Two hypotheses are possible to explain this multitaxon aggregation: trapping in a floodplain gully followed by immediate burial or shelter-sharing. The latter hypothesis is favored after the analysis of the fossil evidence recorded in the South African Karoo Basin.