The documented extinction wiped out dozens of genera around 12,900 years ago. Haynes catalogued the candidate causes: Paul Martin's overkill hypothesis (human hunters), climate change, MacPhee and Marx's hyperdisease, and Firestone's impact. Each has a documented flaw: overkill struggles with the synchrony, climate with the abruptness and the fact these animals survived prior, equally violent swings, disease with the absence of survivors, and impact with the replication wars.
The folk complication: Graham and Stafford's dates suggest horses and camels died 200 years before mammoths and mastodons, while the Murray Springs and Lehner excavations indicate all four taxa terminated together. Whether the kill was one blow or two is still argued trench by trench. Globally, extinctions track human arrival suspiciously well, Australia 46,000 years ago, the Americas 13,000, islands later still.
The claim: the termination is the corpse pile of the planetary reset, and its global near-synchrony with meltwater pulses and the black mat marks one event, not four causes. The pattern, per this reading, is what a fragmented comet's shotgun blast would leave.
Overkill, deep freeze, hyperdisease, or impact: who killed the megafauna, and why does every suspect have an alibi problem?