However, they are also highly diverse and are often used as the basis on which different groups are grouped. The outmost skeleton, also known as the cortical shell, is formed from the fusion of the spines. This shell is then connected to the inner shells by elongated spines/beams that ...
1. Introduction Mesozoic deep-sea sedimentary rocks are widespread, the suc- cessions are relatively complete and little altered, and they have been sampled extensively. Undoubtedly, the appearance of evolutionary innovation among the plankton is enhanced by these circumstances, furthermore, many of ...