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.