Fossil Trees And Forests

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Fossilised trees mystery solved

The trees formed the first-known forests on the planet


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A Cardiff fossil expert has identified a pair of 385-million-year-old trees, thought to be among the world's oldest.
American researchers found fossilised remains in New York state two years ago, but their identity was unknown.

They called in Dr Christopher Berry from Cardiff University, who confirmed the remains are from the Genus Wattieza, a fern-like plant which formed earth's first known forests.

Dr Berry described the discovery as a "spectacular" find.

The upright stumps of fossilised trees were first uncovered after a flash flood in Gilboa, New York, more than a century ago.

But until two further fossils were found two years ago, which had fallen sideways with their trunk, branches, twigs and crown still intact, no-one knew what the entire trees looked like.

The American team called in Dr Berry, who has 17 years of tree fossil expertise, to help.


The tree fossils were found in New York state

Dr Berry, of Cardiff university's School of Earth, Ocean and Planetary Sciences, said it was a "spectacular find" which had allowed scientists to recreate early forest ecosystems.

"This was also a significant moment in the history of the planet," he said.

"The rise of the forests removed a lot of carbon dioxide from the atmosphere. This caused temperatures to drop and the planet became very similar to its present-day condition.

"Branches from the trees would have fallen to the floor and decayed, providing a new food chain for the bugs living below."

Dr Berry worked with colleagues from Binghamton University, New York and from New York State Museum.

Their findings are published in the 19 April edition of the scientific journal Nature.
http://news.bbc.co.uk/2/hi/uk_news/wales/6568233.stm
 
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Published online: 18 April 2007; | doi:10.1038/news070416-10
Full fossil found for the earliest trees
Discovery provides the first view of early forests.
Heidi Ledford


These tall, ancient trees didn't have leaves, but bunches of 'branchlets'.

Frank Mannolini/New York State Museum

Palaeontologists have uncovered a whole sample of the oldest known trees, providing a glimpse of what the Earth's earliest forests might have looked like.

Incomplete fossils of these trees were first found in a rock quarry in upstate New York in the late 1800s and were classified as Eospermatopteris. The trees were thought to live 390 to 350 million years ago. That discovery was in itself exciting, but the fossils contained only the trees' trunks, so no one really knew what the trees looked like.

Now, William Stein of Binghamton University in New York and his colleagues have found two fossils of trees from this period, one of which shows the crown connected to the trunk. The researchers report their findings this week in Nature1.

The work finally finds a home for fossils of the top portion of the tree, which had been found before but not identified as Eospermatopteris crowns. Some palaeontologists had suspected that these fossils were independent plants rather than the tops of trees, with the 'crown' rooted directly into the ground.

The overall architecture of the trees is reminiscent of modern tree ferns, palm trees, and cycads. Eospermatopteris trees predate the evolution of broad, flat leaves like those seen today. Instead they contain what might better be described as photosynthetic 'branchlets' assembled together in fern-like fronds. "At that time, plants were just nothing but sticks," says Stein. "They must have looked really strange, but they were acting as leaves."

Fossils of trunks alone were found in upstate New York in the late 1800s.

W. Stein

Match fossilized tree-tops with their bottoms is often a struggle says Brigitte Meyer-Berthaud, a palaeontologist at the Agricultural Research Centre for International Development in Montpellier, France. "We can find many different parts of the tree, but generally they are not connected," she says. Although the base of the tree is rooted to the ground and tends to stay there, the aerial portions are more easily broken off and transported away, she explains.

Understanding what the first trees looked like can provide a glimpse into the ancient ecology that shaped Earth's chemical cycles, says Thomas Algeo, a geochemist at the University of Cincinnati in Ohio. When land plants became large, around the time of these trees, they had a substantial effect on geochemical cycles, he notes.

Scars down the trunk of the new fossils suggest that the trees littered the forest floor with cast off branches. Algeo believes that litter would have consisted mainly of lignin and cellulose, which bacteria would not have been able to break down. That means the branches would have been broken up by mechanical erosion rather than by decaying to release carbon dioxide.

Over time, litter from Eospermatopteris and other land plants could have pulled a large amount of carbon dioxide out of the atmosphere, he says, leading to an atmospheric cooling that prompted a short ice age starting about 360 million years ago. "That event was probably caused by burial of organic carbon associated with land-plant evolution," Algeo says.

Visit our newsblog to read and post comments about this story.


References
Stein W. E., Mannolini F., VanAller Hernick L., Landing E. & Berry C. M.et al. Nature, 446. 904 - 907 (2007). | Article |
 
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rynner2

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#3
'Early wood' samples reshape plant history
By Mark Kinver, Environment reporter, BBC News

A study of fossilised plant samples has shown that woody plants probably first appeared about 10 million years earlier than previously thought.
The 400-million-year-old samples revealed rings of cells characteristic of wood, a team of scientists observed.
They also suggested that the woody substance appeared to be a mechanism to transport water rather than acting as a support to allow plants to grow taller.
The findings have been published in the journal Science.

"The previous earliest woody plants are of Middle Devonian age (roughly 390 million years old). Our plants are of Early Devonian age, [so about] 400 million years old," explained co-author Phillipe Gerrienne, a geologist from the University of Liege, Belgium.
Dr Gerrienne added that the samples were the first and, to date, only samples of woody plants that had been placed in the Early Devonian period.
"The Middle Devonian plants with wood are shrubs or trees of very small stature. Our plants are much smaller, herbaceous and probably 20-40cm (8-16in) tall ," he told BBC News.
"I would even say that our plants are smaller than some other contemporaneous plants. In fact, all Early Devonian plants were herbaceous, so externally, you would not be able to tell which had wood and which had not.

Dr Gerrienne went on to explain that the team thought that the samples were "early representatives" or ancestors of lignophytes, which is the largest group of plants on Earth today, and includes gymnosperms (such as conifers) and angiosperms (flowering plants).

"Lycophytes (seed-free vascular plants), some bizarre early ferns or early horsetails could produce some wood, but the wood of our plants shows a precise feature (divisions of the cells perpendicularly to the stem surface - see photo above) that is typical of lignophytes," he observed.
He added that the ancient plant samples featured in the study would help researchers understand the first steps of "true wood" evolution.
"For example, our plants show that the rays (horizontal cells) most probably evolved after the other cells in wood (longitudinal cells)."

In addition, Dr Gerrienne said the findings also helped shed light on the initial biological role of the woody substance in early plants.
"Our plants are very small; they have thickened cells just below their epidermis (skin). These two facts suggest that wood was not necessary for support," he concluded.
"This is why we suggest that wood was probably used to enhance the flow of water in the stem. It is only later in evolution that wood was used to improve support.
"The idea that wood first evolved because it improved water conductance had already been suggested by others, but on a theoretical basis only.
"It is nice to have two different plants that illustrate this theoretical inference."

http://www.bbc.co.uk/news/science-environment-14543120
 

rynner2

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#4
'Chinese Pompeii' 300m-year-old forest preserved in ash

Researchers have unearthed a forest in northern China preserved under a layer of ash deposited 300 million years ago.
Preservation of the forest, just west of the Inner Mongolian district of Wuda, has been likened to that of the Italian city of Pompeii.

The researchers were able to "reconstruct" nearly 1,000 sq m of the forest's trees and plant distributions.
This rare insight into how the region once looked is described in Proceedings of the National Academy of Sciences.

The excavations sampled three sites across a large expanse that was covered with about a metre of ash.
Due to the pristine preservation of some of the plants, the team estimate the ash fell over the course of just a few days, felling and damaging some of the trees and plants under its weight but otherwise keeping them intact.

"It's marvelously preserved," said study co-author Hermann Pfefferkorn of the University of Pennsylvania in the US.
"We can stand there and find a branch with the leaves attached, and then we find the next branch and the next branch and the next branch. And then we find the stump from the same tree. That's really exciting."

The team identified six groups of trees, ranging from low-lying tree ferns to now-extinct 25m trees Sigillaria and Cordaites, as well well-preserved specimens of another extinct group called Noeggerathiales.
Based on the findings, the team worked with a painter to depict what the forest would have looked like before the ash cloud descended.

Prof Pfefferkorn said that, as a particularly complete and well-caught moment in time, the forest would serve as a "baseline" for assessing future finds.
"It's like Pompeii," he said. "Pompeii gives us deep insight into Roman culture, but it doesn't say anything about Roman history in and of itself.

"But on the other hand, it elucidates the time before and the time after. This finding is similar. It's a time capsule and therefore it allows us now to interpret what happened before or after much better."

http://www.bbc.co.uk/news/science-environment-17117223
 
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More ancient tree fossils.

The oldest fossil forest in Asia has been discovered in the walls of clay quarries in China.

Researchers say it is the largest example of a Devonian forest, made up of 250,000 square metres of fossilised lycopsid trees. The forest, which covers an area the equivalent of 35 football pitches, is believed to have existed between 359 and 419 million years ago. It is the earliest example of a forest in Asia, according to the study published in the Current Biology journal.

https://www.irishexaminer.com/break...over-oldest-fossil-forest-in-asia-942695.html
 
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