https://www.scientificamerican.com/article/prehistoric-whodunit-new-technique-identifies-what-killed-ancient-animals/

Nowadays detectives can use DNA analysis to help catch a killer. But what happens when a crime scene has been exposed to the elements for thousands of years? DNA does not always stay intact that long—so for a paleontologist trying to figure out what kind of predator killed a long-dead fossil animal, the case often goes cold.

But a new method promises to help researchers identify these ancient killers. It relies on the fact that when a predator gulps down the bones of its prey—say, when a swooping owl snatches and eats a small rodent in the night—the diner's stomach juices leave behind microscopic etchings on the surface of the victim's bones.