When the world’s last northern white rhinoceros male died in March (above), researchers scrambled to save the species—which had only two females left. The answer, The New York Times reports, may be in vitro fertilization. Scientists plan to extract eggs from the remaining females, fertilize them with frozen northern white rhino sperm, and implant the embryos into a southern white rhino, who would act as a surrogate mother. But because the limited genetic material could lead to inbreeding, scientists may use preserved cells from 12 northern white rhinos to create stem cells that could be used to make embryos. But the effort, reported this week in Nature Communications, still has a long way to go before the species gets a second chance at survival.