Some more on the Great Permian Extinction:
http://hannover.park.org/Canada/Museum/extinction/permass.htmlhttp://www.nationalgeographic.com/ngm/0009/feature4/http://geology.wcedu.pima.edu/~jkarlovitz/febpage2.htmGuideline to Scientific Periods:
http://www.ucmp.berkeley.edu/help/timeform.html(mya = million years ago)
Precambrian (4,500 to 543 mya)
......Hadean (4500 to 3800 mya)
......Archaean (3800 to 2500 mya)
......Proterozoic (2500 to 543 mya)
............Vendian (650 to 543 mya)
Phanerozoic (543 mya to today)
.......Paleozoic Era (543 to 248 mya)
.............Cambrian (543 to 490 mya)
.....................Tommotian (530 to 527 mya)
.............Ordovician (490 to 443 mya)
.............Silurian (443 to 417 mya)
.............Devonian (417 to 354 mya)
.............Carboniferous (354 to 290 mya)
...................Mississippian (354 to 323 mya)
...................Pennsylvanian (323 to 290 mya)
.............Permian (290 to 248 mya)
-------------------------THE GREAT PERMIAN EXTINCTION-----------------
.......Mesozoic Era (248 to 65 mya)
.............Triassic (248 to 206 mya) (First appearance of Dinosaurs)
.............Jurassic (206 to 144 mya) (First "Age of Dinosaurs")
.............Cretaceous (144 to 65 mya) (Second "Age of Dinosaurs")
-----------------------------------THE K/T Border---------------------
........Cenozoic Era (65 mya to today) ("Age of Mammals")
..............Tertiary (65 to 1.8 mya)
....................Paleocene (65 to 54.8 mya)
....................Eocene 54.8 to 33.7 mya)
....................Oligocene (33.7 to 23.8 mya)
....................Miocene (23.8 to 5.3 mya)
....................Pliocene (5.3 to 1.8 mya)
..............Quaternary (1.8 mya to today)
.....................Pleistocene (1.8 mya to 10,000 years ago)
.....................Holocene (10,000 years ago to today)