 Catherine Forster, in a 1984 paper on the ecology of "Tenontosaurus", used this as evidence to suggest that "Tenontosaurus" populations did not arrive in the Bighorn Basin area until the time of the late Little Sheep Mudstone Member.At the time "Tenontosaurus" first appeared in Wyoming and Montana (the early Albian age), the regions climate was arid to semi-arid, dry, with seasonal periods of rainfall and occasional droughts.However, during a period of a few million years, the climate in the region shifted to one of increased rainfall, and the environment became subtropical to tropical, with river deltas, floodplains, and forests with swampy inlets reminiscent of modern Louisiana, though marked dry seasons persisted to create savannah-like environments as well.