The ancestors of plants

No one knows for sure when the first land plants appeared, but according to geologist Renato Ramos, from the National Museum of the Federal University of Rio de Janeiro, this happened 470 million years ago, in the Ordovician period. The ancient ancestors of plants were small and primitive and always lived near water.

The ancestors of plants

During the Ordovician and Silurian periods (which followed), the Earth's atmosphere was filled with carbon dioxide, a substance used by plants to photosynthesize and thus obtain energy. Levels of this gas in the atmosphere at the time were about 15 times higher than they are today, and the abundance of this gas allowed plants to survive and multiply, which gave rise to the first forests at the end of the Devonian period, between 390 and 360 million years ago.

The ancestors of plants

Later, a major expansion of forests occurred during the Carboniferous period, between 360 and 300 million years ago. This led to an increase in the level of oxygen in the atmosphere. The gas, produced by plants through photosynthesis, came to make up about 32% of the Earth's atmosphere – today, the figure is 21%.

The ancestors of plants

“Along with the occupation of the continents by plants, insects emerged,” says Renato. “This, in turn, enabled the arrival of the first amphibians on land, sheltered by the shade of the plants, where they found abundant food.”

Later, during the Cretaceous period – between 145 and 65 million years ago – forests already covered all parts of the world, including Antarctica. “Small mammals took shelter in burrows in tree trunks. They only came out in hiding to feed on insects, plants and dinosaur eggs,” says the geologist.

The ancestors of plants

The emergence of forests favored not only the evolution of amphibians and mammals, but also of other animal groups, such as birds. Have you ever imagined what a world would be like without them?