After the plant dies, some of its carbon remains locked up in the lignins and can become buried in the Earth through geologic processes, preventing those carbon atoms from returning to the atmosphere and effectively lowering atmospheric carbon dioxide.
Fossil fuels like coal and oil are made from plant material, containing carbon that was taken out of the atmosphere and buried in swamps millions of years ago. Releasing those same carbon atoms back into the atmosphere by burning fossil fuels appears to be causing the Earth to get warmer again, according to many studies. Hedges and his research team made their surprising discoveries about the early appearance on Earth of the first land plants and fungi by studying as many of the genes as possible of their descendants — the species of plants and fungi living today.
They began by sifting through their molecular fingerprints — the unique sequences of amino-acid building blocks — in many thousands of genes from hundreds of species archived in the public gene-sequence databases. Eventually, they found genes common to living species of fungi, plants, and animals that met the researchers' stringent criteria for use as "molecular clocks.
By detailed comparisons of the amino-acid sequences of individual genes among numbers of species, the scientists identified those genes that had accumulated mutations at a fairly constant rate relative to one another during their evolution.
The scientists calibrated each of their gene clocks with evolutionary events well established by fossil studies, primarily those in the history of animals. The second one, which seems to have occurred when algae were beginning to make the transition to terrestrial life, produced genes for adaptive features such as ultraviolet-light protection and the ability to form a root system and interact with terrestrial microbes. A much earlier burst occurred while the algae were still fully underwater and making the transition from unicellularity to multicellularity.
To Tang and Xiao, the physical characteristics in the fossils suggest that species was a chlorophyte, one of the two main lineages of green algae — but not the one that most scientists think produced land plants. That ancient algae specimens therefore seem to have evolved their multicellular, complex structure earlier and independently of the burst of genetic creativity that Paps and his colleagues deduced from reconstruction.
In fact, most experts agree that many of the features in early green algae could have evolved independently more than once in a phenomenon known as convergent evolution. The discrepancy may therefore highlight the real lesson to take away from these discoveries: Any confident statement about exactly when and how the ancestors of land plants evolved may always involve an oversimplification of the zigzagging path that evolution often takes. This article was reprinted on Wired.
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Moderators are staffed during regular business hours New York time and can only accept comments written in English. We care about your data, and we'd like to use cookies to give you a smooth browsing experience. Although the first land plants were responsible for these mass deaths in their ocean-dwelling neighbours , Lenton says they themselves probably came out of the Ordovician ice age largely unscathed.
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Birds in the Amazon are adapting to climate change by getting smaller COP26 news: Real progress made but more emissions cuts are needed New COP26 draft text adds caveats to fossil fuel subsidies phase-out Don't miss: Cowboy Bebop gets a live-action remake on Netflix Puzzle-solving great apes: The shared abilities underpinning language. The evolution of plant life on Earth is fundamental to the history of our planet. It has provided resources and habitats for animals and influenced climate on a global scale.
Now, Museum scientists are part of a multi-institutional team transforming our understanding of this most formative episode in Earth's history. Their latest findings, published in the journals Proceedings of the National Academy of Sciences and Current Biology, show that land plants evolved about million years earlier than previously thought.
New data and analysis show that plant life began colonising land million years ago, during the Cambrian Period, around the same time as the emergence of the first land animals. Lowly liverworts have been generally considered the most primitive of existing plants. Liverworts are flowerless, spore-producing plants that lack features characteristic of other land plants, such as roots, or pores on their surfaces for gas and water exchange. It has generally been assumed that the earliest land plants were liverwort-like and therefore much research effort has been poured into studying this group and developing it as a model for the ancestral land plant.
The research published in Current Biology shows this assumption is incorrect. In the family tree of plants, liverworts and mosses are in fact sisters, and both are distant cousins to the ancestors of ferns and flowers.
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