Geologic Time Scale
A Geological Time Scale is a system of chronological measurement relating to stratigraphy to time that is used by scientists. The following is the timescale used by the USU Eastern Prehistoric Museum.
Cenozoic
Holocene Quaternary
Present - 0.0117 Ma
Pleistocene Quaternary
0.0117 - 2.588 Ma
- Paleo-Indian
- Huntington mammoth
- Saber-toothed cat
- Short-faced bear
- Dire wolf
- Long-horned bison
Plioene Neogene
2.588 - 5.333 Ma
Miocene Neogene
5.333 - 23.03 Ma
Oligocene Plaeogene
23.03 - 33.9 Ma
Eocene Plaeogene
33.9 - 56.0 Ma
Paleocene Plaeogene
56.0 - 66.0 Ma
Mesozoic
Upper Cretaceous
66.0 - 100.5 Ma
- Chasmosaurus tracks
- Prosaurolophus tracks
Lower Cretaceous
100.5 - ~145.0 Ma
- Peloroplites
- Animantrax
- Gastonia
- Utahraptor
Upper Jurassic
~145.0 - 163.5 ±1.0 Ma
- Allosaurus
- Camptosaurus
- Camarasaurus
- Stegosaurus
- Torvosaurus
Middle Jurrasic
163.5 ±1.0 - 174.1 ±1.0 Ma
Lower Jurrasic
174.1 ±1.0 - 201.3 ±0.2 Ma
Upper Triassic
201.3 ±0.2 - ~235 Ma
Middle Triassic
~235 - 247.2 Ma
Lower Triassic
247.2 - 252.2 ±0.5 Ma
Paleozoic
Upper Permian
252.2 ±0.5 - 259.9 ±0.4 Ma
Middle Permian
259.9 ±0.4 - 272.3 ±0.5 Ma
Lower Permian
272.3 ±0.5 - 298.9 ±0.2 Ma
- Dimetrodon
Upper Pennsylvanian Carboniferous
298.9 ±0.2 -307.0 ±0.1 Ma
Middle Pennsylvanian Carboniferous
307.0 ±0.1 - 315.2 ±0.2 Ma
Lower Pennsylvanian Carboniferous
315.2 ±0.2 - 323.2 ±0.4 Ma
Upper Mississippian Carboniferous
323.2 ±0.4 - 330.9 ±0.2 Ma
Middle Mississippian Carboniferous
330.9 ±0.2 - 346.7 ±0.4Ma
Lower Mississippian Carboniferous
346.7 ±0.4 - 358.9 ±0.4 Ma
Upper Devonian
358.9 ±0.4 - 382.7 ±1.6 Ma
Middle Devonian
382.7 ±1.6 - 393.3 ±1.2 Ma
Lower Devonian
393.3 ±1.2 - 418.2 ±3.2 Ma
Pridoli Silurian
418.2 ±3.2 - 423.0 ±2.3 Ma
Ludlow Silurian
423.0 ±2.3 - 427.4 ±0.5 Ma
Wenlock Silurian
427.4 ±0.5 - 433.4.0 ±0.8 Ma
Llandovery Silurian
433.4.0 ±0.8 - 443.4 ±1.5 Ma
Upper Ordovician
443.4 ±1.5 - 458.4 ±0.9 Ma
Middle Ordovician
458.4 ±0.9 - 470.0 ±1.4 Ma
Lower Ordovician
470.0 ±1.9 - 485.4 ±1.9 Ma
Upper Cambrian
485.4 ±1.9 - ~497 Ma
Middle Cambrian
~497 - ~521 Ma
Lower Cambrian
~521 - ~529 Ma
Precambrian