Download SR 47(6) (Living Fossils) - NOPR

Living Fossils
T
HE cycads are a group of very primitive
plants that are very similar in appearance
to palms although they are not related to it.
Like Cockroaches, cycads too are called
“living fossils,” because they have persisted
almost unchanged down the ages. As a
group, cycads reached their evolutionary
pinnacle about 200 million years ago and,
since then, their population has been on a
downswing. Fossil cycads aged about 240
million years ago share many characteristics
with the cycads alive today. Just like the
Wollemi Pine, cycads too may well have
provided food for herbivorous dinosaurs
and fossilized cycads are frequently found
in the same rocks as dinosaur bones. The
Jurassic Period is sometimes called the “Age
of cycads” because they were so common
then.
Living cycads are represented by
about 300 or so species and about a dozen
or less genera. They usually grow in tropical
and subtropical regions although a few are
found in temperate regions. Cycads have a
central trunk topped by a whorl of leaves,
usually without any side branches. Like palm
leaves, cycad leaves too have a central stalk
flanked by rows of narrow leaflets on both
sides. Cycads are gymnosperms, which
means “naked seed” and as such, they bear
cones, but never a true flower. Male and
female cones are borne on separate plants.
All species of cycads are endangered.
According to the IUCN—World
Conservation Union’s Cycad Specialist
Group—cycads represent one of the most
threatened plant groups in the world.
Dangers to living population are largely due
to habitat destruction and over-collection
of specimens; and so these plants are
covered by the import/export restrictions
of the Convention on International Trade
in Endangered Species (CITES).
That even fossilized cycads can
go “extinct” because of overzealous
collection is exemplified by what happened
at the Cycad National Monument, USA. In
1892, F. H. Cole was exploring government
owned land near Minnekahta, USA when
he discovered one of the world’s greatest
surface concentrations of fossilized
cycads—actually an “entire fossil forest of
cycads.”
Cole sent photographs of the
fossil cycads to geologist Professor Henry
Newton of the Smithsonian Institution. In
1893, Professor Thomas MacBride
published the first description of the site.
Paleobotanist George Reber Wieland at
Yale University was concerned about the
Cycads
Untouched by Time
vulnerability to plunder and used the
Homestead Act to gain ownership of 320
acres containing the fossils. In 1922 he
returned the land to the government, on
condition that a national monument was
created there.
This site was proclaimed a
national monument on 21 October 1922.
The US President declared that the national
monument was being established because
there are: “..... rich Mesozoic deposits of
fossil cycads and other characteristic
examples of paleobotany, which are of great
scientific interest and value....”
Unfortunately, even before the Fossil Cycad
National Monument formally came into
existence, illegal collectors managed to
carry away all the fossil cycads that had
made the site worthy of national park status.
On September 1, 1957, the United States
Congress voted to de-authorize the Fossil
Cycad National Monument. (More details
are
available
at
(http://
w w w. n a t u r e . n p s . g o v / G e o l o g y /
paleontology/pub/grd3_3/focy1.htm )
This was not the only loss that
the fossil cycads faced. Prior to 1988, the
state fossil of South Dakota, USA, was the
cycad. When illegal collecting destroyed the
Fossil Cycad National Monument, both the
park and the cycad lost their official status.
However, scientists seem to have
learnt their lesson well. Today there are
Cycad Societies dedicated to the
conservation of cycads across the world.
Let us hope that these ancient plants that
have survived the ravages of time will
triumph over human exploitation as well.
Dr Sukanya Datta
Scientist NISCAIR posted to Director General's
Technical Cell, CSIR HQ
Email: [email protected]
SCIENCE REPORTER, June 2010
55