By Jacopo Prisco, CNN (CNN) — A piece of woolly mammoth skin excavated from the Siberian permafrost has been found to contain fossil chromosomes in a first-of-its-kind discovery, according to a new study. Researchers unearthed the 52,000-year-old remains in 2018 near the village of Belaya Gora in northeastern Siberia, where freezing temperatures helped preserve the structure of the chromosomes — tiny threadlike structures that carry genetic mate…