Well the specifics are the lineage which includes sharks, we found stuff that might be sharks but hard to prove are definitely sharks that’s 450 million years old (fossil sharklike scales)

And, this is copypaste from Snopes:

The earliest known fossil evidence of sharks (or their ancestors) are “shark-like scales” that date back to 450 million years ago, according to the National History Museum in London. However, whether these scales adorned “true sharks” or “shark-like animals” is an issue debated by the scientific community.

Nonetheless, scientists largely agree that, according to DNA evidence, living sharks, rays, and deep-sea fish called chimeras likely began evolving around 420 million years ago.