Polysaccharide Structure and the Problems of Phylogenesis

Era Period Beginning, millions of years ago Duration, millions of years Time of chordate animals appearance 

Cenozoic Quaternary Neogene 70 Evolution of human being Divergence of mammals 

Proterozoic Archean Cambrian 600 100 Jawless chordates. Appearance of eukaryotic cell approximately 1.4 billion years ago Appearance of first prokaryotic cells approximately 3.5 billion years ago 

The evolutional development and appearance of a variety of species took place as a result of the genetic rules of evolution. The evolution of genomes went in a direction wherein the amount of the genetic information was increased, that is, an increase of DNA content. Thus, mycloplasm, the simplest bacterial cell without a polysaccharide external layer, has only 0.5 x 10 pairs of nucleotides in its DNA and can code about 470 general proteins. The bacteria with polysaccharide cell shells (murein) have 3 x 10 pairs of the nucleic bases in its DNA. Monocellular eukaryotic cells, like yeast, include about 15 x 10 pairs of the nucleic basis. 

By comparing embryos of different classes and groups of chordates, K. von Baer had postulated a law of embryonic similarity, which states that embryos of the same phylum of animals are very similar at the initial stages of the developments. Later (in 1866), on the basis of these and other data, E. Haeckel formulated a basic law of biogenesis that states ontogenesis is a short repetition of phylogenesis. Early stages of animal and human 

---