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Bridgerian
The Bridgerian North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), typically set from 50,300,000 to 46,200,000 years BP lasting . It is usually considered to overlap the Ypresian and Lutetian within the Eocene epoch. The Bridgerian is preceded by the Wasatchian and followed by the Uintan NALMA stages. Substages The Bridgerian is considered to contain the following substages: *Twinbuttean: Lower boundary source of the base of the Bridgerian (approximate). *Lutetian which is contained within the Middle Eocene sharing the lower boundary. The Lutetian overlaps with New Zealand's Arnold epoch, Dannevirke Dannevirke ( "Earthworks (archaeology), work of the Danes", a reference to Danevirke; or ''Tāmaki-nui-a-Rua'', the area where the town is) is a rural service town in the Manawatū-Whanganui region of the North Island, New Zealand. It is the ... epoch, Bortonian stage, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wasatchian
The Wasatchian North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), typically set from 55,400,000 to 50,300,000 years Before Present, BP lasting . It is usually considered to be within the Eocene, more specifically the Early Eocene. The Wasatchian is preceded by the Clarkforkian and followed by the Bridgerian NALMA stages. Definition The age is named after the Wasatch Formation, a highly fossiliferous stratigraphic unit stretching across six of the United States from Idaho and Montana in the north through Utah and Wyoming to Colorado and New Mexico in the south. Substages The Wasatchian is considered to contain the following substages: * Sandcouleean: shares lower boundary with the beginning of the Wasatchian age and shares upper boundary with the base of the Graybullian. * Graybullian: shares lower boundary with the end of the Sandcouleean subage and upper boundary with the ba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uintan
The Uintan North American Stage is the North American faunal stage, typically set from 46,200,000 to 42,000,000 years before present lasting 4.2 million years. The Uintan Stage is a key part of the North American land mammal age, North American Land Mammal Age. In the Uinta Basin, a thriving subtropical ecosystem was formed at around 46.0 million years ago. It falls within the Eocene epoch, preceded by the Bridgerian and followed by the Duchesnean NALMA stages. The Uinta Formation is a key piece of this geologic stage. Mammalian Machairodontinae, sabretooths evolved and became dominant predators in the now-Western United States. These included ''Apataelurus'', ''Diegoaelurus,'' and ''Machaeroides''. Substages The Uintan is considered to be contained within the Lutetian sharing the upper boundary and contains the following substages: *Late/Upper Uintan: Lower boundary source of the base of the Uintan (approximate). *Early/Lower Uintan: Upper boundary source of the base of the Duches ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
