This notebook guides learners through analyzing fossil, sediment, and ecological evidence to evaluate competing explanations for a mass death event using scientific reasoning and paleontological data interpretation. This resource forms part of the following teaching guides: • What Happened at Cleveland-Lloyd Dinosaur Quarry? • Who Wins and Who Loses in a Rapidly Changing Forest? • What Dinosaur Did These Bones Come From? • Decomposition - It’s a Dirt-y Job! • Insect Apocalypse