Origin of Life: early land life in algae fossil (Introduction)

by David Turell @, Friday, March 27, 2020, 00:33 (10 days ago) @ David Turell

A new finding, which may show first land life:


"Around 500 million years ago — when the Earth was already a ripe 4 billion years old — the first green plants appeared on dry land. Precisely how this occurred is still one of the big mysteries of evolution. Before then, terrestrial land was home only to microbial life. The first green plants to find their way out of the water were not the soaring trees or even the little shrubs of our present world. They were most likely soft and mossy, with shallow roots and few of the adaptations they would later evolve to survive and thrive on dry land. And though scientists agree that these plants evolved from some kinds of seaweed, we know comparatively little about those green algal ancestors."


"The recently unearthed tiny fossil, smaller than a single grain of rice, appears to be the world’s oldest known specimen of green algae: It rolls back the clock on the confirmed existence of these algae by a staggering 200 million years. “It’s very daunting. A billion years — that’s at least five times older than the oldest dinosaurs,” said Xiao, who is a senior author on the Nature Ecology & Evolution paper that announced the discovery. “It’s before any animals. The world is very, very different from what we know today.'”

"He excavated some from formations near the city of Dalian in northern China, where geological maps had told him he was likely to find the green-hued rocks containing fossils from that remote epoch. But it wasn’t until he got back to the lab and examined them under an electron microscope that he understood the value of what he had found: “I was very excited when I saw the first piece of this green seaweed,” he said. “These kinds of fossils are totally new to science."

"Ancient as the fossilized algae are, they seem to have many of the characteristics also seen in much later green seaweeds. It isn’t just that they were clearly photosynthetic and multicellular — traits that help to define seaweeds but have murky evolutionary origins. “They have leaves, they have branches,” Tang said.


"The evolutionary innovations seen in Tang’s fossil may have helped to set algae on a path that eventually led them ashore by about 470 million years ago. But the transition to land life would probably have begun hundreds of millions of years earlier, with green algae adapting to survive in damp soil or sand that was subject to temporary drying. Evolutionary biologists have generally believed that this transformation probably arose in parallel with the appearance of more complex multicellular structures, some of which lent themselves to these adaptations."

Comment: All types of life started in the seas. When continents poked up into dry land, life got there some how. And the animals arrived and ate the plants and other animals. Life appeared 3.6-8 by ago and this development took a long time to happen.

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