pteridosperm

例句：

1. 1. This species is a member of the Pteridosperms, which are characterized by their lack of limbs.
   这种物种属于无脊椎动物纲，其特征是没有四肢。
2. 2.The discovery of this fossilized pteridosperm has shed new light on the evolution of flight in birds.
   这种化石化的无脊椎动物的发现为鸟类飞行进化提供了新的见解。
3. 3. In the field of paleontology, the study of Pteridosperms is essential for understanding the history of life on Earth.
   在古生物学领域，研究无脊椎动物对于理解地球上生命的历史至关重要。