| | Introduction to the Prymnesiophyta (Site not responding. Last check: 2007-10-21) |
 | | The plates accumulate on the bottom of the ocean as the organisms die, and there contribute to the formation of ocean sediments, carbonate oozes, and rocks such as the Mesozoic limestones and chalks. |
 | | The group made a sudden and rapid appearance of new forms in the early Jurassic, and reached its greatest abundance in the Late Cretaceous. |
 | | Near the end of the Cretaceous, the coccolithophores suffered a mass extinction of groups; two-thirds of the 50 genera disappear at that time, though many new groups appear in the Paleocene. |
| www.ucmp.berkeley.edu /chromista/prymnesiophyta.html (518 words) |