Discovery of an Early Permian claw from Antarctica extends the fossil record of crayfish by ∼65 m.y. and demonstrates that decapod crustaceans had radiated into freshwater habitats by the late Paleozoic. Burrows in Lower Triassic rocks of Antarctica are among the oldest apparently constructed by crayfish. Their morphology is similar to modern crayfish burrows, and this demonstrates that burrowing behavior was established early in the evolution of this group. The new discoveries show that the earliest Permian crayfish were distributed in high paleolatitudes of southernmost Pangea, where they lived in freshwater lakes fed by glacial meltwater. Modern crayfish habitat, used as a guide to crayfish temperature tolerance, indicates that summer temperatures of streams and lakes near the South Pole that supported the crayfish probably reached 10–20 °C during Permian-Triassic interglacial intervals.
- Geological Society of America