Taking the early Triassic animal fossils together with the evidence for extensive forests leads to the speculation that Triassic Antarctica was a refuge ecosystem where survivors of the Permian extinction rode out the event and the challenging environments of the early Triassic that prevailed in many other parts of the globe. You recall the other day I mentioned a paper that suggested that the tropical Triassic Earth might have been “lethally hot” and that ocean temperatures in the Triassic might have been so hot that life could not survive. The polar regions might have been enough cooler that they provided this refuge for life, which would have expanded across the planet as conditions became more favorable later in the Triassic and Jurassic.

Source: History of the Earth: September 21. Triassic Antarctica