Uintan
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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.[3] The Uintan Stage is a key part of the 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.[4] The Uinta Formation is a key piece of this geologic stage. Mammalian sabretooths evolved and became dominant predators in the now-Western United States. These included Apataelurus, Diegoaelurus, and Machaeroides.[5][6]
| Uintan | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chronology | |||||||||||||
| |||||||||||||
| Formerly part of | Tertiary Period/System | ||||||||||||
| Etymology | |||||||||||||
| Name formality | Formal | ||||||||||||
| Usage information | |||||||||||||
| Celestial body | Earth | ||||||||||||
| Regional usage | Global (ICS) | ||||||||||||
| Time scale(s) used | ICS Time Scale | ||||||||||||
| Definition | |||||||||||||
| Chronological unit | Age | ||||||||||||
| Stratigraphic unit | Stage | ||||||||||||
| Time span formality | Formal | ||||||||||||
| Upper boundary definition candidates | Calcareous nannofossil near LAD of the Haptophyte Reticulofenestra reticulata | ||||||||||||
| Upper boundary GSSP candidate section(s) | Contessa highway section, Gubbio, Central Apennines, Italy | ||||||||||||
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 Duchesnean (approximate)
