Ping.
If you actually read the paper they explain what the study actually supports fairly clearly. Mitochondrial DNA is not subject to natural selection in the same way as phenotypical DNA (code for actual adaptive changes). What they measured was the way this DNA “drifts” or acquires noisy differences across populations over time. They found that 90% of all species today have roughly the same amount of drift in their mitochondrial DNA. This is consistent with the sudden reduction of a population to very small numbers due to some environmental catastrophe or pandemic. This effectively “resets the drift clock” since the populations restart from about the same baseline as the surviving ancestors. If 90% of species populations were reduced about 100,000 to 200,000 years ago they would all show about the same degree of drift when measured now. This doesn’t mean the dinosaurs didn’t live 65 million years ago and that our phenotypic DNA doesn’t clearly show the validity of natural selection.