| System/ Period | Series/ Epoch | Stage/ Age | Age (Ma) | |
|---|---|---|---|---|
| Quaternary | Pleistocene | Gelasian | younger | |
| Neogene | Pliocene | Piacenzian | 2.58 | 3.600 |
| Zanclean | 3.600 | 5.333 | ||
| Miocene | Messinian | 5.333 | 7.246 | |
| Tortonian | 7.246 | 11.63 | ||
| Serravallian | 11.63 | 13.82 | ||
| Langhian | 13.82 | 15.97 | ||
| Burdigalian | 15.97 | 20.44 | ||
| Aquitanian | 20.44 | 23.03 | ||
| Paleogene | Oligocene | Chattian | older | |
| Subdivision of the Neogene Period according to theICS, as of 2017[1] | ||||
TheEarly Miocene (also known asLower Miocene) is a sub-epoch of theMioceneEpoch made up of twostages: theAquitanian andBurdigalian stages.[2][3]
The sub-epoch lasted from 23.03 ± 0.05Ma to 15.97 ± 0.05 Ma (million years ago). It was preceded by theOligocene epoch. As the climate started to get cooler, the landscape started to change. New mammals evolved to replace the extinct animals of the Oligocene epoch. The first members of thehyena andweasel family started to evolve to replace the extinctHyaenodon,entelodonts andbear-dogs. Thechalicotheres survived the Oligocene epoch. A new genus of entelodont calledDaeodon evolved in order to adapt to the new habitats and hunt the new prey animals of the Early Miocene epoch; it quickly became the top predator ofNorth America. But it became extinct due tocompetition fromAmphicyon, a newcomer fromEurasia.Amphicyon bestedDaeodon because thebear-dog's larger brain, sharper teeth and longer legs built for longer chases helped it to overcome its prey.
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