Rapid and Early Post-Flood Mammalian Diversification Evidenced in the Green River Formation

The Eocene Green River Formation (GRF) is a series of basin deposits in Wyoming, Utah, and Colorado (USA), famous for its well-preserved fish and other fossils. The GRF’s post-Flood lacustrine status is confirmed by a whole host of geological evidences. Depending on the post-Flood timescale used, the GRF was probably in place between decades to several centuries following the Flood. Its early post-Flood date is confirmed by Hyracotherium, the first animals in an intrabaraminic biological trajectory. For having such an early post-Flood date, the rocks of the GRF contain a remarkable disparity of fossils, including a greater mammal disparity than the area currently supports. Present are about 230 families (proxies for baramins) in about 104 orders, representing every kingdom of organisms. Species diversity within baramins seems to have been very low soon after the Flood, suggesting that first-order intrabaraminic diversification may be modeled following low diversity biodispersal. This suggests baramins dispersed at low diversity and diversification occurred at the termini of post-Flood dispersion paths