The fossil record is a catalog of unexplained deaths, almost by definition. Of course part of the job of the paleontologist is to attempt to provide an explanation: climate change, competition from other species, giant asteroids colliding, the list of possible reasons is long, and the cases made range from modest to very persuasive. I don’t know how convincing it is, but one I have shown to students is this video about the probable cause of death of the famous female Australopithecine, Lucy.
The fossil was discovered by Donald Johansen and his colleagues in 1974. They came up with the name because the famous Beatles song “Lucy in the Sky with Diamonds” was playing on the camp record player the night of the discovery. Johansen’s website, Becoming Human, has a wealth of information on this and other aspects of human evolution.
I will let the video speak for itself rather than give details, but just to comment, as I do for my students, that past discoveries do not necessarily disappear into the sediment of accumulating new ones, but occasionally are resurrected and brought to life by the application of new ideas and methods. This is a classic approach to science.