Tuesday, August 7, 2012

Fossil Hunting: Science and Hobby

Dr Abe V Rotor

Legends are rich in stories of the supernatural when gods do the impossible to the awe and fear of mortals, such as turning man into rock. Or wood into rock. For who would deny the markings of every tissue of the demised tree - its xylem vessels, phloem which carry manufactured food from the leaves, the pith or dead center of the wood? In fact one can count the age of the tree when it died by counting the annular rings. And how long had the tree died. The circumstances of its death, and the events like drought, flood, fire that it had undergone.

Top: Teachers view the Fossil Collection of the Museum of Natural History, UPLB, Laguna; author (left) studies fossil of a Nautillus. Right: fossils of Amonites, and ancient fish fossils.  

Next time you visit a quarry, or landscape supplier, or simply walking along a river bed, or rocky cliff, be keen at the possible presence of petrified wood. If there are more clues to the fossil you can even tell what tree it was. Is it already extinct? Is it the ancestor of modern species? What if the tree has not changed, evidenced by its similarity with its living progeny?

Indeed fossils are nature's geologic timepieces; they take us thousands, if not millions of years back. Didn't Charles Darwin gauge the stages of evolution of plants and animals through paleontology - the science of the study of fossils?

At first I didn't see it, until the tides left it in shallow water. It is a fossil of a very big staghorn coral, its base cut like the anther of a deer after the mating season. So clean did it appear I can count the number of years the coral lived. But that is deceiving because corals grow very slow. It takes fifty long years to grow to the size of a man's head. Each ring therefore, is compounded with other rings, making it difficult to tell the exact age of the fossil. A clear break may be an indication of an extreme condition of the environment that left such mark.

Around the fossil are many fossils of small organisms, other corals and shells. Fossils are known by their total age by combining the age of the fossil itself and the age of the surrounding rock.

How do fossils retain their form and structure even to the detail? Well, calcium carbonate seeps into the cells, and tissues, and in this particular case, into the fine structures like pores of the coral skeleton where the compound solidifies hard - harder than the mold itself. It's a skeleton in a skeleton, so to speak. Through hundreds or thousand of years the mold disintegrates leaving behind the hardened calcium compound. The process is also the same in wood turning into rock - petrified rock.
Here is a fossil of a bivalve - a big Tridachna, as large as the shell of its progeny shown in the lower photo. This shell is a receptacle of holy water at the entrance of Mt. Carmel Church QC. Shells survive adverse conditions of the environment, and as such also retain their original shape and form. Sand and silt become sedimentary rock entombing the shell until it is discovered through erosion and other means.
Fossils are made in a different way such as a hairy caterpillar stuck in oozing latex of rubber tree. The latex solidifies and hardens into rock, the same way an insect is engulfed in oozing resinous substance of pine tree. The resin hardens into a clear transparent material with the doomed insect or any other creature clearly visible. Resin turns into amber. Remember Jurassic Park movie? A mosquito after feeding on blood of a dinosaur was trapped in amber. The DNA of the extinct monster was reconstructed from the mosquito's food blood. Of course this is fiction. But Flash Gordon and Jules Verne proved beyond being just fiction writers.

 Fossil of a bivalve
 Petrified wood is actually rock which bears the exact likeness of the original wood. The species can be traced to present specimens.   

Everyday we encounter fossils and pseudo 
fossils we simply call skeletons, or artifacts if they did not directly come from living things. Fossils are always in the making. There is no ceasing since the appearance of life on earth, and ever expanding with increasing biodiversity of the living world. 

Making of a fossil.  Hairy caterpillar trapped in latex becomes a fossil thousands, millions of years from now. 

They are the remains of living things that survive time and circumstances, and of luck or fate as people put it. The older and better preserved fossils are, the more significant is the discovery - and the more we realize the secrets they reveal. Scientists reconstruct fossils close to their original form and virtual reality, complete with the organism's movements, sounds, habitat, special effects included. Thanks to advanced technology and fine arts.

Toys are then patterned after these reconstructed fossils. I know of children who grew up with collections of dinosaurs, birds, mammals, fish- all reconstructions from fossils. Many of these children grew into scientists and naturalists. I know of other children who were more interested with toy cartoon characters. They took a different career path, less meaningful and fulfilling than that of the latter children.

Geologic time is not constant though it may be contiguum. There are intervening factors we may not and never know. And if this were the case, we say, we have yet to discover the "missing link." Such was the predicament of Darwin in his theory of evolution, the bewilderment of Wallace before him, and the deceiving simplicity of Lamarck theory to decipher correctly the path of evolution. Fossils reveal the web of life as a labyrinth. We can only appreciate the early works of other paleontologists that Cuvier and Huxley who could only make inferences about life in the past and the present. In spite of all these, the world looks at all these men as pioneers and greatest fossil hunters.

Do you like to be a fossil hunter, too? ~