Fossil records organism

Early students of the origin of life were misled because they believed that Earth was very young, in part because no methods were available for dating ancient events. Today, suitable methods exist for determining the age of materials that are billions of years old, and the fossil record of ancient organisms has vastly improved. The evolution of living organisms... 

Evidence for early collisions is also present in the fossil record, suggesting that the diversity of species present on Earth has been reduced considerably on several occasions, perhaps removing some 90 per cent of species. Some organisms... 

Starting about 1.5 billion years ago, the fossil record begins to show evidence of larger and more complex organisms, probably the earliest eukaryotic cells (Fig. 1-35). 

Details of the evolutionary path from prokaryotes to eukaryotes cannot be deduced from the fossil record alone, but morphological and biochemical comparisons of modern organisms have suggested a sequence of events consistent with the fossil evidence. 

Biochemical evolution refers to changes over geologic time of the fundamental composition of organic components—e.g., the sequence of amino acids in protein molecules. The best documented example of biochemical evolution is that of the respiratory pigment haemoglobin, and the relation of its evolution to the fossil record has been summarized recently (58). Many of the monographs on comparative biochemistry have discussed biochemical evolution (59, 60, 61), and the reader is... 

Eglington, G. Organic molecules as chemical fossils — the molecular fossil record, in Cosmochemistry and the origin of life, in Cosmochemistry and the origin of life (ed. Ponnamperuma, C.) p. 323, Dordrecht, Boston, London, D. Reidel, P. C. 1983... 

Organisms appear in the fossil record in the sequence in which they finished their genomic evolution, i.e., the simplest first. Many different clones of similar levels of complexity finish simultaneously in many places. Simple organisms appear first in one locality and spread from there slowly increasing in number and variety. Al 1 appear in succession, one from another. 

The earliest forms of life were simple single- and multi-celled organisms. These early forms of life are rarely found in the fossil record because there are few places on Earth where very old rocks still exist, and because these tiny organisms consisted only of soft tissue. 

Since there is limited information available as to how found fossil organisms lived or how they reproduced in the past, their true affinities may never be known. In addition, most fungi are not very well preserved in the fossil record, so it has been difficult to interpret the fossil record of fungi, leaving open the possibility of an earlier, unrecorded history (Gray Shear, 1992 Taylor Taylor, 1993 Taylor et al., 1994 Hibbett et al., 1995). 

Traditionally, phylogenetic trees were constructed relying on morphology and on the fossil records. Nowadays, however, they are constructed from comparisons of DNA or protein sequences in living organisms. Because of the antiquity of... 

The fossil record indicates that macroscopic, multicellular organisms appeared approximately 600 million years ago. Most of the organisms familiar to us consist of many cells. For example, an adult human being contains approximately 100,000,000,000,000 cells. The cells that make up different organs are distinct and, even within one organ, many different cell types are present. Nonetheless, the DNA sequence in each cell is identical. The differences between cell types are the result of differences in how these genes are expressed. 

In summary, the potential for the use of age-related biomarkers is tremendous. For precise age-dating, however, it is necessary to establish the relationship between certain compounds and the evolution of certain plants or organisms. This is clearly a very time consuming process and requires a great deal of work and correlation between biomarkers and the fossil record. Once the ratios are established and successfully calibrated for the oils, they can be potentially very powerful. As mentioned above, it is generally oils that are recovered from drilling operations and not source rocks, so the more information that can be recovered from oils the more useful the results. 

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