由于人们很难对早古生代深海沉积岩进行测年 ,所以对寒武纪—奥陶纪海洋中外骨骼浮游生物在深海沉积物中的作用知之甚少。这些外骨骼生物大都保存在造山带的主缝合带 ,如哈萨克斯坦地区。放射虫是已知的能够保存内骨骼的最古老的浮游生物。它们在早古生代首次出现 ,那时还没有? Little is known about the role of plankton in the Cambrian-Ordovician oceans in deep-sea sediments because of the difficulty of dating the deep-sea sediments of the Early Paleozoic. Most of these exoskeletal organisms are preserved in the main suture zone of the orogenic belt, such as the Kazakhstan region. Radiolarians are known as the oldest plankton that holds internal bones. They first appeared in the early Paleozoic, but not yet?