Physical evidence of cosmic impact doesn't always come from craters or sediment layers. Sometimes it's preserved in bone. He's examining micrometeorite debris patterns found embedded in Alaskan mammoth tusks and a Siberian bison skull, small hemispherical impact zones surrounded by carbonized rings. The impacts are clustered on one side of the specimens, suggesting a directional bombardment rather than random atmospheric entry. This is the kind of evidence that changes how we think about megafaunal extinction events at the end of the Pleistocene. If micrometeorites struck with enough force to shatter and carbonize organic material, what else was happening in that same moment? The distribution pattern points to a specific event, not gradual environmental change. It's one more thread in a larger story about catastrophic forcing mechanisms that shaped the boundary between ice age and Holocene.