Златозар Боев [Zlatozar Boev]
29 December 1997 ·
volume 8 · pp. 137–146 ·
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Abstract: [no abstract available originally]
[Summary]: A brief review of the evolution rates, species composition and the species number of birds as a class is made. Modern ornithology knows even about 0.7 per cent of all avian species, both fossil and recent lived on Earth since the Triassic period during the last 220 million years. The greatest number of recent avian families appeared in the Middle Eocene. The faster growth of species variety is established for the Oligocene-Miocene boundary, while the last mass-extinction in birds occurred in the end of the Late Pliocene.