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Oldest Pine Tree Fossils Discovered

Found in a rock quarry, the fossils date back to the time of the dinosaurs Continue reading →

Trees from the genus Pinus are so common across the Northern Hemisphere that it probably seems as if they've been here forever. But now we know that they date back at least 140 million years to the Cretaceous period, when dinosaurs still stomped around the Earth.

Scientists from the Department of Earth Sciences at Royal Holloway, University of London, have found the oldest pine tree fossils yet to be discovered, in a rock quarry in the Canadian province of Nova Scotia.

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Science magazine reports that one charred twig, just a half of a centimeter in diameter, has small divots where pine needle shoots once poked out. The specimens are some 11 million years older than the oldest previously discovered pine fossil.

Interestingly, the fossils appear to be charred from a fire. When the tree was alive, the atmosphere had high oxygen levels,and the temperature was high. That created prime conditions for fires. Pine trees actually have evolved to burn and spread forest fires, so that their pine cones can germinate on the charred forest floor without competition.

"The fossils show that wildfires raged through the earliest pine forests and probably shaped the evolution of this important tree," researcher Howard Falcon-Lang said in a press release.

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The specimens, which are described in Geology journal, were preserved as charcoal within rocks from a quarry.

"It was only when I digested (the samples) in acid that these beautiful fossils fell out," Dr Falcon-Lang told BBC News.

Pine trees such as these ones in Russia have existed for at least 140 million years, according to newly discovered fossil evidence.

Seen here close-up under a dissecting microscope, the flowering plant

Amborella trichopoda

is the oldest known existing species of petal-bearing plants on Earth. Now in a series of reports published today in the journal Science, molecular geneticists have unlocked the genomic secrets of

Amborella

, and with it clues as to why flowers display such successful genetic diversity.

Many of

Amborella

's genes were distinct from those of non-flowering plants. In its mitochondrial DNA, which tends to change less than nuclear DNA,

Amborella

showed a shared affiliation with mosses and green algae. Biologist Danny W. Rice of Indiana University and his team hypothesize that wounded

Amborella

plants obtained the shared mitochondrial genomes as a result of horizontal gene transfer between these other organisms it was living in close proximity with millions of years ago. Here,

Amborella

genomic DNA is shown in blue, chloroplast DNA in green, and mitochondrial DNA in red.

Indeed, the team discovered that

Amborella

's mitochondrial genome provides the largest example of horizontal gene transfer – the acquisition of foreign genes from other species – in any organism. Shown here are male flowers of

Amborella

.

The Indiana University team -- working with biologists from the U.S. Department of Energy, Penn State University, and the Institute of Research for Development in New Caledonia -- showed for the first time that an organelle genome has captured an entire foreign genome, in this case, four of them: three green algae and one moss. It is also the first description of a land plant acquiring genes from green algae. Shown here are female flowers of

Amborella

.

"The

Amborella

mitochondrial genome is like the old lady in the song who swallows a fly, and then a spider, a bird, a cat, and so on, all the way to a horse, at which point, finally, "she's dead of course," said co-author of the study Jeff Palmer, a Distinguished Professor in the Indiana University Bloomington College of Arts and Sciences' Department of Biology. Shown here are

Amborella

female flowers and fruits.

"Likewise, the

Amborella

genome has swallowed whole mitochondrial genomes, of varying sizes, from a broad range of land plants and green algae. But instead of bursting from all this extra, mostly useless DNA, or purging the DNA, it's held on to it for tens of millions of years. So you can think of this genome as a constipated glutton, that is, a glutton that has swallowed whole genomes from other plants and algae and also retained them in remarkably intact form for eons," said Palmer in a press release. Shown here are

Amborella

in fruit.

View from the summit of Mt. Aoupine, New Caledonia. The flowering

Amborella

, whose mitochondrial genome is amazingly rich in foreign genes and even genomes, is endemic to the island of New Caledonia. The research on

Amborella

shows "compelling evidence that mitochondrial fusion is the driving force for mitochondrial gene transfer and that incompatibility in the mechanism of mitochondrial fusion between different phyla – plants versus animals or fungi – provides the major barrier to unconstrained mitochondrial 'sex' across the evolutionary tree of life," said Palmer.

The southwest-Australian Christmas tree,

Nuytsia floribunda

, which parasitizes the roots of grasses to obtain water and minerals. This parasite belongs to the group of parasitic plants (Santalales) from which the

Amborella

mitochondrial genome has captured many foreign genes by horizontal gene transfer.

A parasitic flowering plant (

Amyema scandens

) blooming in New Caledonia from its epicortical roots, which, like mistletoe, grow along the branch of its host tree. This parasite belongs to the same group of parasitic plants (Santalales) from which the

Amborella

mitochondrial genome has captured many foreign genes.

A parasitic flowering plant (

Hachettea austro-caledonica

) emerging from the ground to flower. This plant parasitizes the roots of other flowering plants and belongs to the group of parasitic plants (Santalales) from which the

Amborella

mitochondrial genome has captured many foreign genes. Picture taken in New Caledonia, the South Pacific island on which both

Amborella

and

Hachettea

are endemic.