Erin Garcia de Jesus in her article, "The oldest animal DNA ever recovered reveals mammoths’ evolution" explores how mammoth DNA can indicate the bone structure of ancestors, how the species may have went extinct, and so much more. The DNA was extracted from three ancient mammoth teeth in northeast Siberia. The two oldest specimens from the Krestovka and Adycha lineages dated back from 1.2 to 1 million years ago. In addition, the third specimen from the Chukochya was determined to be 800,000 to 500,000 years old. The analysis of all three specimen led researchers to conclude that the Krestovka and Adycha lineages were of two different mammoth species. Researchers also recognized that many mutations, such as shaggy hair, helped mammoths adapt better to cold climates. The ancient DNA was quite fragile and created limitations for the study. It was noted that the permafrost of northeast Siberia made DNA extraction from the mammoth teeth much more feasible.
Jesús, E. G. (2021, February 17). The oldest animal DNA ever recovered reveals mammoths' evolution. Retrieved from https://www.sciencenews.org/article/oldest-animal-dna-ever-recovered-mammoth-evolution
T. van der Valk et al. Million-year-old DNA sheds light on the genomic history of mammoths. Nature. Published online February 17, 2021. doi: 10.1038/s41586-021-03224-9.