rhachides

noun

1. (form-of, plural)plural of rhachis

   “However, the rhachides in the proximal portion of the tail of Zhenyuanlong appear to be longer than those of Microraptor 5 6 and Changyuraptor 10, which had relatively small and simple feathers proximally on the tail but much larger and more complex feathers distally, which expanded outwards into a large fan.”