With over 30,000 species worldwide, the ray fins are currently the largest group of fish. These bony fish were not always as numerous, however. Losses of other fish species, such as cartilaginous fish, helped them to spread successfully. As paleontologists from the University of Zurich together with international researchers reveal, a series of serious extinction events between 300 to 200 million years ago played a central role in the development of today’s fish fauna.
Fuente : http://www.alphagalileo.org/ViewItem.aspx?ItemId=1...
Fuente : http://www.alphagalileo.org/ViewItem.aspx?ItemId=1...