A Brief History of Geologic Time

200 Mya to 180 Mya

 200 Mya to 180 Mya

usage notes: Mya points to "millions of years ago I referens to "before the present;"

 

 

 

 200 Mya: Pangea existed as present continents united.

200 Mya to 145 Mya: This is the duration of the Jurassic geological Period. The Jurassic Period fell between the Triassic and Cretaceous Periods,

~ The super continent Pangaea began to drift apart during this Period.

~ There was lots of life, wet climate, and lush vegetation. Many new dinosaurs appeared. Conifers appeared. Mammals were common, but small. There is evidence of early birds and lizards, our first evidence of them.

~ There was a "minor"extinction toward the end of this period.

200,000,000 BP: At this very beginning of the Jurassic Period

Pangea exists. Present continents become defined but are still united. 

 

201,000,000 BP to 152,000,000 BP: Jurassic Period: This period was been divided into the Early, Middle, and Late Jurassic. The Early Jurassic is made up of four ages: the Hettangia, the Sineemurian,, the Pliensbachisan, and the Toarcian. We have begun a geological timeline. I'll add that there were already some small mammals around at this early age,

 

 

 

 

260 Mya to 240 Mya

 260 Mya to 240 Mya

 Usage notes: "Mya" means "million years ago" These dates are amazing close approximations, but are subject to adjustments

259. 0.4 Mya, Lopingian, Wuchiapingian: Marking the end of the Permo-Carboniferous glaciation.

254.14 Mya, Paleozoic, Permian, Lopingian, Changhsingian: Land masses unite into supercontinent Pangaea and creating the Appalachian range.

251.9 Mya to 201.3 Mya: Duration of the Triassic Period of the Mesozoic Era. The Triassic Period is between the Permian and Cretaceous Periods.

~ First evidence of mammals occurred in this Period. One was a mouse size critter.

~ This geologic period ended with a mass extinction of species. So, 251,900,000 BP marked a mass extinction of life.

251,900,000 BP to 201,300,000 BP: Triassic Period: This time has been called the Triassic Period. The Triassic Period falls after the Permian Period and before the Jurassic Period. First evidence of mammals appear, a mouse like critter is found to lie within the Period. This geologic period ended with a mass extinction of species.