Fossils

What is a fossil? The word is Latin, and it means,“dug up.” One of the earliest known research publications to use this term was Agricola's work on systematic[Page 995]mineralogy, De natura fossilium.It wasn't until Lamarck's Hydrogeologie was published in 1802 that the term was restricted to “the still recognizable remains of organized bodies.” Even as late as the mid-1800s, the concept of fossilization was, except in the minds of a very few, considered the result of a recent worldwide deluge. For over 1,000 years, just the discussion of events beyond the scope of the biblical account of creation could cause one to end up in prison or worse. Sir Walter Raleigh is one of the better-known of these victims. His conviction for treason and subsequent beheading was precipitated in part by his suggestion, in his volume entitled History of the World, that civilization was older than the biblical account allowed. The current definition of the term fossil has thus only very recently evolved.

Source: © iStockphoto/Fred van Engelen.

Currently, the term “fossil” refers to any remains or traces of once-living organisms. Although this definition is much narrower than the original term's Latin origin, it still covers a broad range of preserved structures. A fossil may be as simple as a single preserved mark in a sediment or as complex as a mummified dinosaur. It may be as old as 3.7 billion years or as recent as a few hundred. Fossils are as varied and diverse as the life forms that produced them and the climatic and structural conditions that preserved them. However, this vast array of preserved evidence of past life has survived to the present through only a very few natural processes. These processes include permineralization, tracks and traces, molds and casts, carbonization, and original preservation. The following is a brief examination of each of these processes and a description of the types of fossils preserved through each process.

It should be noted that one process is common to all fossil preservation:the process of protection. Regardless of the method of preservation, if the specimen had not been suitably protected, it would not have survived. Most often, this protection involves being buried and remaining undisturbed until discovery. Rapid encasement and removal of oxygen from the environment are the key protection criteria for virtually all fossils. These conditions are necessary to keep the organic tissue from either deteriorating or becoming damaged while the other processes take place.