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Triassic period – pine trees and pterodactyls

By |2018-04-21T11:56:46-07:00June 25th, 2017|Biology, Geology|

A turtle in the desert During the Triassic period (about 248 to 199 million years ago), most of Earth's land continued to stick together in one big supercontinent, Pangaea. Because the middle of Pangaea was so far from the oceans, it was very dry there, like a desert. The whole world was generally [...]

Tertiary period – mammals and mountains

By |2018-08-22T05:19:59-07:00June 25th, 2017|Biology, Geology|

Tertiary period: Large animals evolved like moose Dinosaurs become extinct The Tertiary period begins with the catastrophe that killed off the dinosaurs at the end of the Cretaceous Period, about 65 million years ago. And the Tertiary lasts down to 1.8 million years ago. Mammals become more common With nearly all of the dinosaurs [...]

Quaternary period – modern times

By |2018-11-09T07:50:38-07:00June 24th, 2017|Biology, Geology|

The Quaternary Period includes today - big cities and all When was the Quaternary Period? The Quaternary period began about 1.8 million years ago (1,800,000 years ago), coming after the Tertiary. The Quaternary is still going on today - we live in the Quaternary period. So far, it's a much shorter period than [...]

What happened in the Cretaceous Period?

By |2018-04-21T11:56:37-07:00June 24th, 2017|Geology|

Volcano erupting During the Cretaceous period, beginning about 145 million years ago, the continents continued to drift away from each other, so that the mammals, birds, and dinosaurs on different continents evolved separately and got more and more different from each other. As the continents separated, the climate got cooler and rainier, and [...]

What is an aurochs? Central Asian Environment

By |2019-02-06T08:28:00-07:00May 31st, 2017|Central Asia, Environment|

Cave painting of a herd of aurochs (about 14000 BC) When did the aurochs evolve? Around fifty million years ago, after the dinosaurs died, large mammals started to evolve from smaller mammals that came earlier. Because grass had evolved only recently, about 100 million years ago, there weren't yet very many animals that ate grass, [...]

Eggs – Evolution and Biology

By |2019-03-22T08:11:09-07:00May 29th, 2017|Biology|

Fish eggs: Egg evolution starts with soft eggs like these When did the first eggs evolve? The earliest living creatures made babies by dividing themselves in half, so that one cell became two cells. But about 1.4 billion years ago, some creatures with more than one cell began to develop specialized cells that [...]

Reptile and Mammal Skeletons – Evolution and Biology

By |2018-04-16T09:09:50-07:00May 28th, 2017|Biology|

Evolution of skeletons: Skeleton of a dinosaur Evolution of skeletons From frogs, there evolved reptiles like crocodiles and dinosaurs. Some of these reptiles lived mostly or entirely on land, so they needed stronger bones that could hold them up when they weren't in the water. And most reptiles ate meat, so, like fish, [...]

Why do we have fingers? Skeletons, Evolution, and Biology

By |2017-05-28T00:38:23-07:00May 28th, 2017|Biology|

Human hand bones The first fingers and toes evolved from earlier fish fins about 400 million years ago. During the Devonian period, the oceans were very shallow, and some fish evolved to be able to push themselves out of the water to breathe the air. For this, they needed stronger fins that they [...]

How do animals breathe? Respiration, Evolution, Biology

By |2018-04-21T11:56:44-07:00May 27th, 2017|Biology|

Fish gills The first cells, which evolved about 3.8 billion years ago, needed carbon dioxide to live and not oxygen. They needed the carbon dioxide to help them break down molecules to get energy out of them, and they were able to get the carbon dioxide they needed from the oceans they lived [...]