Actual DNA fragments from 2.4 million years ago have been recovered from the permafrost in Greenland enabling researchers to reconstruct the local ecosystem of that time. The fragments of ancient DNA found in the ice sheet came from more than 135 different species.
To put this into context: our own species, Homo sapiens only originated about 300.000 years ago.
https://www.the-scientist.com/news-opinion/2-million-year-old-dna-is-oldest-ever-recovered-70820
The Scientist Magazine®2.4 Million-Year-Old DNA Is Oldest Ever RecoveredThe DNA fragments collected from permafrost in northern Greenland unlock insights into an ancient ecosystem.