At the abandoned quarry in New York, fossilized trees from 386 million
years ago were uncovered. It is believed
the extensive network of trees, which would have spread from New York all the
way into Pennsylvania and beyond, is around 386 million years old.
The forest of Cairo is 2 to 3 million years old than what was thought
to be the world’s oldest forest at Gilboa, also in New York State and around 40
km away from the Cairo site.
The new findings, which have been published in the journal Current
Biology, have thrown new light on the evolution of trees and the transformative
role they played in shaping the world we live in today.
A team led by scientists at Binghamton University, New York State
Museum and Cardiff University have mapped over 3,000 square meters of the
forest at the abandoned quarry in the foothills of the Catskill Mountains in
the Hudson Valley.
Their investigations showed that the forest was home to at least two
types of trees: cladoxylopsids, primitive tree-fern-like plants, which lacked
flat green leaves, and which also grew in vast numbers at Gilboa; and
Archaeopteris, which had a conifer-like woody trunk and frond-like branches
which had green flattened leaves.
A single example of a third type of tree was also uncovered, which
remained unidentified but could possibly have been a lycopod.
All these trees reproduced using only spores rather than seeds.
The team also reported a ‘spectacular’ and extensive network of roots
which were more than eleven meters in length in some places which belonged to
the Archaeopteris trees.
It is these long-lived woody roots, with multiple levels of branching
and small, short-lived perpendicular feeder roots, that transformed the
interactions of plants and soils and were therefore pivotal to the co-evolution
of forests and the atmosphere, the researchers state.
Until this point in time, trees such as the cladoxylopsids only had
ribbon-like and mostly unbranched roots which had to be constantly replaced as
the plant above ground grew. They believe the forest was eventually wiped out
by a flood due to the presence of many fish fossils that were also visible on
the surface of the quarry.
“It is surprising to see plants which were previously thought to have
had mutually exclusive habitat preferences growing together on the ancient
Catskill delta,” said co-author of the study Dr. Chris Berry from Cardiff
University’s School of Earth and Ocean Sciences.
“This would have looked like a fairly open forest with small to
moderate sized coniferous-looking trees with individual and clumped tree-fern
like plants of possibly smaller size growing between them.”
The research team say that the Cairo forest is older than the one at
Gilboa because the fossils were lower down in the sequence of rocks that occur
in the Catskill mountains.
“In order to really understand how trees began to draw down carbon
dioxide from the atmosphere, we need to understand the ecology and habitats of
the very earliest forests, and their rooting systems,” continued Dr. Berry.
“These remarkable findings have allowed us to move away from the
generalities of the importance of large plants growing in forests, to the
specifics of which plants, in which habitats, in which types of ecology were
driving the processes of global change. We have literally been able to drill
into the fossil soil between the trees and are now able to investigate
geochemical changes to the soil with our colleagues at Sheffield University.
“We are really getting a handle on the transition of the Earth to a
forested planet.”
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