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What are snakes? Evolution and biology

By |2018-04-15T00:32:41-07:00September 16th, 2017|Biology|

Two pythons Snakes evolved from lizards only about 150 million years ago, during the Jurassic Period. This is during the time of the dinosaurs, about the same time that the first birds evolved from small dinosaurs. Like birds and mammals, though, snakes really began to take over after most of the dinosaurs died about 95 million years ago, at [...]

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 [...]

Permian period – Reptiles and pine trees

By |2018-04-21T11:56:38-07:00June 24th, 2017|Biology, Geology|

Crocodiles About 290 million years ago, the Carboniferous period ended and the Permian period began. Almost all of the land on Earth grouped together in one big supercontinent we call Pangaea, which reached all the way from the North Pole to the South Pole. With all the land grouped together, the climate got [...]

Carboniferous Period – Geology

By |2019-02-28T09:47:59-07:00June 23rd, 2017|Geology|

Dragonfly When was the Carboniferous period? With the end of the Devonian period about 359 million years ago, the Carboniferous period got started. More about the Devonian Quick summary of geological eras All our geology articles What was the Earth like then? Most of the land on Earth was warm and swampy, which [...]

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, [...]

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 [...]

Reproductive System – Evolution and Biology

By |2018-04-16T08:57:39-07:00May 27th, 2017|Biology|

Reproduction: Hydra budding new hydras RNA and DNA molecules The first form of reproduction began about four billion years ago, when first RNA molecules and then DNA molecules began to make new copies of themselves by letting amino acids hook on to the parent molecule and then splitting them off. All reproduction since then [...]

What are turtles? Biology and Evolution

By |2018-04-21T11:56:44-07:00May 26th, 2017|Biology|

Evolution of turtles: Seychelles tortoise (Jardin des Plantes, Paris) Evolution of turtles The first turtles began to evolve from earlier reptiles about 225 million years ago, during the Triassic period. By about 210 million years ago, they looked pretty much like modern turtles. Turtles are one of the oldest kinds of reptiles that [...]

What are reptiles? Biology and Evolution

By |2018-04-21T11:56:35-07:00May 26th, 2017|Biology|

Boa Constrictor snake Some kinds of amphibians evolved into reptiles about 300 million years ago. At this time, plate tectonics had moved more and more of the land on Earth into one big continent called Pangaea. All the land being together changed the weather so that it was drier and colder than before. That [...]