If you are not referring to the mammoth study, "52k.txt" might relate to one of the following:
The article details how a mammoth that died 52,000 years ago in Siberia was preserved so perfectly that scientists could map its —a feat previously thought impossible for ancient samples. 52k.txt
Shortly after death, the mammoth’s skin underwent a spontaneous "freeze-drying" process in the Siberian cold. If you are not referring to the mammoth study, "52k