CONNECTING AND MISSING LINKS 



Our fossil record begins with the dawning of the Palaeozoic 

 era, some 500,000,000 years ago, but the date of the origin 

 of life was vastly more remote, for when the fossil record 

 actually begins not only is life fully manifest, but the numer- 

 ous animal stocks that constitute its invertebrate division are 

 already well established. These earliest known animals are 

 far more diverse and complex than the most primitive imag- 

 inable organisms, some of which yet exist — such as the slime 

 molds and the bacteria described as prototrophic (literally 

 "first feeding"). Thus the missing links in the early evolu- 

 tion of animal life constitute for millions of years the entire 

 chain. There is, however, no doubt in the scientific mind 

 that the oldest known fossils imply, with the assurance of 

 certainty, a long antecedent evolution, much of which, in 

 spite of the fact that palaeontology is silent, can be deduced 

 from the sister sciences of comparative anatomy and embry- 

 ology. The reason the record anterior to this time is blank 

 is because of the nature of the organisms themselves. Com- 

 posed as they were largely of soft parts with no limy skele- 

 tons, or shells, they apparently left little to be preserved in 

 the rocks of ancient time. Consequently, save for certain 

 remarkable impressions, yet to be described, little of the 

 actual nature of these ancestral types is known, except by 

 inference, until they had established what has been called 

 the lime-secreting habit, which was formed by animals in 

 mid-Cambrian time, by plants somewhat earlier. True, there 

 are masses of limestone, iron ore, and graphite in the pre- 

 Palaeozoic rocks, all of which are regarded as largely of 

 organic origin, but, although their presence is indirect evi- 

 dence of the existence of organisms in this remote time, it 

 reveals nothing of their nature. 



One notable exception lies on the flank of Mount Wapiti, 

 near Field, in British Columbia, where, in a small area of 



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