K-T Boundary (K-Pg). EXTINCTION of the DINOSAURS (65 million years). - 20 g

The K-T (or K-Pg) boundary is a geological marker that records the mass extinction event 65 million years ago, famously associated with the demise of dinosaurs. Samples related to this boundary may contain extraterrestrial material, iridium anomalies, or impact ejecta from the asteroid collision theorized to have triggered the extinction. Collectible specimens linked to this event provide tangible connections to one of Earth's most significant biological transitions, studied extensively in paleontology and geology.