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Devonian Period – Gondwana, ferns, lungfish

By |2019-05-07T05:56:55-07:00June 24th, 2017|Biology, Geology|

Coelocanth: a fish from the Devonian period When was the Devonian period? Four hundred and sixteen million years ago, when the Silurian period ended and the Devonian period began, most of the land on Earth was clumped together into a supercontinent called Gondwana. Silurian period Plate tectonics All our geology articles Life in [...]

Seeds – Plant reproduction – Biology

By |2018-04-13T17:51:52-07:00May 30th, 2017|Biology|

Evolution of seeds: Dandelion seeds What is a seed? A seed is the egg cell of a plant, with a hard wrapper around it so it can survive on its own. The earliest plants with seeds evolved from plants with spores during the late Devonian period, about 360 million years ago. The seeds [...]

Plant reproduction – Biology – Science

By |2018-04-13T17:52:39-07:00May 30th, 2017|Biology|

Cell division The very earliest photosynthesizing plants on Earth, about 3 billion years ago, had only one cell, and they reproduced the way most one-celled creatures do, by mitosis: splitting themselves in half. By about two billion years ago, some of these cells began to split themselves in a more sophisticated way, called [...]

Evolution of bones – Skeletons and Biology

By |2017-05-28T00:44:16-07:00May 28th, 2017|Biology|

A fish skeleton One-celled animals don't have any support system that holds them in a certain shape. Plants do have a support system, but it's the cellulose in the cell wall of each cell, rather than bones. Early multi-celled animals like jellyfish and sponges and worms also didn't have skeletons, but beginning with [...]

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 [...]

Digestive System – Biology and Evolution

By |2019-05-07T20:07:23-07:00May 26th, 2017|Biology|

Digestive system: A hydra eating: the mouth is where all the tentacles come together,near the center of the picture.The hydra is eating the round bug in its stomach. Before digestive systems... Starting about 3.8 billion years ago, during the Archaean Era, one-celled creatures were the earliest living things. They just floated in the ocean [...]

Lungfish – Evolution of Fish

By |2018-04-15T17:26:06-07:00May 26th, 2017|Biology|

Evolution of fish: a lungfish About 400 million years ago, during the Devonian period, the Earth was going through an especially warm period. Some of the smaller oceans and lakes were drying up, leaving big muddy puddles all around them. This was no good for fish, which had less room to swim around [...]