英语语法分析

Feathers can have a pennaceous vane and a plumulaceous base.

单一支羽毛也可以由顶端为正羽、基部为绒羽组合而成。

Xu calls it a "four-winged" dinosaur because it had long, pennaceous feathers on its arms and legs.

因为其前后肢上都存在着较长的羽翮，因此徐星将它称之为“四翼”恐龙。

Eventually, dense rows of interlocking barbs formed a flat surface: the basic blueprint of the so-called pennaceous feathers of modern birds.

最终，成行的浓密互连羽支形成了平滑表面：即现代鸟类的羽翮结构基本形成。