Resin truths

A RECENT expedition to New Jersey
organised by the American Museum of
Natural History in New York, US,
returned with a sizable haul from the
fossilised world. The team led by David
Grimaldi uncovered one of the richest
deposits of amber ever found. The
deposits found in central New Jersey are
estimated to be around 95-65 million
years old. "It is scientifically the most
important of all amber fossils," says
Grimaldi.

Around 100 species of insects and
plants trapped in the ancient tree sap are
unknown to the world. Three tiny flowers - that had perhaps fallen from an
oak tree - have been recovered from
approximately 40 kg of amber. Their
discovery is of great significance to the
scientific community as the flowers date
back to some 90 million years, when
dinosaurs inhabited the earth. The flowers are the oldest fully preserved ones to
be found in amber. They may hold clues
to the origin of the flowering plants that
currently dominate the earth.

Apart from the oldest flowers, the
New Jersey amber deposit contains
other specimens like the world's oldest
fossilised mosquito with proboscis
sharp enough to pierce a dinosaur's
thick skin; the oldest moth whose
mouth indicates its transition from a
biting insect to one that sucks the nectarof flowers; and the oldest biting
black fly.

Although amber is found mostly in
conifers like pines, it occurs even in
sequoias and cedars apart from certain
decidous trees. The dried up tree resin,
is believed to be a defence mechanism
against wood-boring insects. It trickles
down the bark of the wounded trees
encapsulating the insect and hermetically
sealing the injured part of the trunk
simultaneously. When the 'trees with the
dried res 'in fall later, they get buried in
the soft sediment found at the bottom of
still and shallow waters. Over millions
of years these resin molecules consolidate, forming a string of resin-beads
which resemble plastic because of their
chemical inertness and, air and water-
tight nature. The amber is not selective
in nature rather, it devours anything
that comes its way.

Amber fossils give us clues as to the
where and how of the preservation of
certain plant and animal characteristics
or mannerisms. They may also reveal
whether or not insects and flowers help
each other in evolution. Preserved in
amber are images from the past like
mites riding on the backs of sweat bees,
a leaf beetle spitting out a stream of noxious bubbles in self defense and spiders mating.

Although amber is an excellent preserver of ancient life forms, it is unable to prevent the fragmentation Of DNA
strands. DNA found in amber is scientifically very interesting as it happens to be
the best preserved protein on earth, with
the amber dehydrating the captive and
the terpenes in the resin acting as a fixative. Although scientifically the DNA may
be of importance, biologically it is
worthless since it cannot be of use as a
blueprint to generate life.

Genetic material has been extracted
from a 17 million-year-old magnolia
leaf, a 30 million -year- old termite and
a 120 million-year-old weevil, but
unlike what happens in the movie
Jurassic Park, scientists have not been
able to re-create a living entity from bits
of DNA.

Surprisingly, amber deposits that do
not contain fossils may not be important to scientists and biologists, but
command value as precious stones and
are much sought after by artists and
jewellers. Amber is found in a variety of
colours (about 250 shades) like white,
red, blue and green.