Pre–Younger Dryas megafaunal extirpation at Rancho La Brea linked to fire-driven state shift

Abstract

The cause, or causes, of the Pleistocene megafaunal extinctions have been difficult to establish, in part because poor spatiotemporal resolution in the fossil record hinders alignment of species disappearances with archeological and environmental data. We obtained 172 new radiocarbon dates on megafauna from Rancho La Brea in California spanning 15.6 to 10.0 thousand calendar years before present (ka). Seven species of extinct megafauna disappeared by 12.9 ka, before the onset of the Younger Dryas. Comparison with high-resolution regional datasets revealed that these disappearances coincided with an ecological state shift that followed aridification and vegetation changes during the Bølling-Allerød (14.69 to 12.89 ka). Time-series modeling implicates large-scale fires as the primary cause of the extirpations, and the catalyst of this state shift may have been mounting human impacts in a drying, warming, and increasingly fire-prone ecosystem.

Quantifying the effects of exceptional fossil preservation on the global availability of phylogenetic data in deep time

“…"Lagersta ¨tten" [58][59][60] are unusually rare confluences of deposition, taphonomy, and diagenesis that produce exceptionally preserved fossil assemblages. Lagersta ¨tten are found across billions of years of geologic time [61] and include some of the most famous and intensely-studied fossil assemblages on the planet [62][63][64][65][66]. The biological information we gain from rare lagersta ¨tten deposits often substantially exceeds what is preserved in the vast majority of "normal" fossil deposits, and as such have been identified as having an anomalous impact on studies of ecology, diversification and extinction through time [4,6,59,61,67].…”