The fossil record

Most commercial marine diatomite deposits exploit accumulations resulting from large blooms of diatoms that occurred ia the oceans during the Miocene geological epoch. Diatomite sediments older than the Jurassic period are rare in the fossil record. Commercial deposits of diatomite are accumulations of the fossil skeletons, which can occur in beds as thick as 900 m in some locations (5). Marine deposits must have been formed on the bottom of protected basins or other bodies of quiet water, undisturbed by strong currents, in an environment similar to the existing Santa Barbara Channel or Gulf of California (3,6). 

Succession of flora and fauna refers to the deposition of sedimentary material, which will include the remains of plant and animal life that existed at the time of the deposition of these rock particles. The fossils of these plants and animals will be found in the rock formations that result from the deposition. The presence, absence, or change of the plant and animal life within a sequence of the geologic column provide important information that allows for the correlation of rock formations (and, thereby, relative time) from location to location. Also, the fossil records within sequences give important information regarding the evolution of life through geologic time. 

Scientists do not believe that life is arising from non-life on Earth today, but, if life originated on Earth, as it apparently did, it must have developed from non-living materials. Current scientific views of when and how life might have originated and evolved are based upon imaginative chemical experiments in the laboratory, combined with studies of the fossil record and ways of dating events in the remote past. 

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... 

The fossil record of African antelopes (Mammalia, Bovidae) in relation to human evolution. In Vrba, E.S., Denton, G.H., Partridge, T.C. and Burekle, L.H., eds., Paleoclimate and Evolution. New Haven, CT, Yale University Press 385-424. 

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... 

The complex processes of growth, reproduction, collecting nutrition and movement, perhaps even carbon-fixing processes such as photosynthesis, have to be performed to get to the simplest life forms found in the fossil records. There can be no time to dawdle complex life was formed rapidly perhaps over a period of 100-500 million years, reaching a living form close to something that we would recognise today as a bacterium. 

Schopf JW (2000) The fossil record tracing the roots of the cyanobacterial lineage. In Whitton BA, Potts M (eds) The ecology of cyanobacteria their diversity in time and space. Kluwer Academic, Netherlands, pp 13-35... 

In the 1960, it was noticed that substitutions in some amino acid sequences seemed to occur at a roughly constant rate over time (Zuckerkandl and Pauling, 1965). This is the well known molecular clock hypothesis. For a particular protein such as cytochrome c or myoglobin, it was noticed that there was a linear relationship between divergences of pairs of sequences, as measured by numbers of amino acid differences, and divergences of the species, as measured by dates from the fossil record. There is still considerable debate as to how accurate the molecular clock may be and as to how it might vary systematically depending on the species, type of protein, and kinds of substitutions that are counted. 

Unstable and evanescent analogical (no gene) life of primordial times (Woolfson 2000) is difficult to imagine in the perspective of secondary metabolites. Digital (DNA) life has more concrete foundations, dating to at least 3,450 My ago, according to cyanobacterial remains (Mojzsis 1996). The first eizkaryotes are latecomers, appeared in the fossil record 2,500 My ago (Schopf 1993), and... 

We can start with vertebrates. Vertebrates are speciabzed to oxic environments, because their mitochondria are specialized to oxic environments. Vertebrates go back maybe 500 Myr in the fossil record (Benton and Donoghue 2007), so this makes sense. Vertebrates arose after the oceans were oxic and moved onto land at a time when they had evolved lungs and were able to crawl. 

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... 

Conway Morris, S. (1 981) Parasites and the fossil record. Parasitology 82, 489-509. 

Royer DL, Wilf P, Janesko DA, Kowalski EA, Dilcher DL (2005) Correlations of climate and plant ecology to leaf size and shape Potential proxies for the fossil record. Am J Botany 92 1141-1151... 

Collect modern reference material from different light intensity regimes (sun and shade leaves) and check for the possibility to recognize and separate these (for instance through cell wall undulation index (Ktirschner 1997). Often, sun-morphotypes are preferentially preserved in the fossil record. If sun and shade leaves can be separated, develop morphotype-specific calibration curves to minimize potential error. 

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