This fossil “map” has Archaeopteris – an ancient group of plants with large woody roots and leafy branches, similar to modern trees, according to a report from Binghamton University. Previously, the earliest evidence of Archaeopteris leading scientists to think that this group of plants did not appear until 20 million years later.
The development of these early forests depended on the evolution of precursors. “I think the key factor is evolution, anatomical developments that allow for more complex branching of trees.”Berry said. Plants have evolved, he said. “genetic toolkit” to be able to create structures like trees today.
For example, primitive branching systems evolved just before the Devonian, during the Silurian (443.8–419.2 million years ago), while the first root systems appeared in the early Devonian, according to the Brooklyn Botanic Garden. The traits of the trees then offered major advantages, especially the ability to reach upward to absorb sunlight.
However, some environmental changes may have helped at least one important plant trait to form. Megaphyllsthe leaves common today with their characteristic branching veins, grew much larger than their ancestors, allowing them to absorb more sunlight. They first appeared about 390 million years ago but did not become widespread until 30 million years later, in the late Devonian period.
This delay occurred because high CO2 levels caused the Earth to become too hot for the large megaphylls. They absorbed too much sunlight and became too hot. However, CO2 levels dropped rapidly during the Devonian, which gave the megaphylls a huge advantage. The Earth cooled, while the large megaphylls were able to develop more holes called stomata to absorb more CO2. These leaves may then have helped fuel the growth of forests.
According to VnExpress