https://www.sciencenews.org/article/50-million-year-old-fossil-captures-swimming-school-fish
Avid fisherman here, so this one piqued my interest. Not sure I buy into the collapsing sand dune theory of how the fish were (mostly) preserved in swimming orientation, but I found the repulsion/attraction discussion intriguing as i have seen that behavior by menhadden countless times while fishing in the Atlantic. Its easy to assume extinct animals acted similar to their modern cousins, but rare to see behavioral proof.
The abstract for the paper is here:
https://royalsocietypublishing.org/doi/10.1098/rspb.2019.0891