Why are modern sturgeons called chondrosteans despite having bony plates?

Modern sturgeons are classified as chondrosteans because the term Chondrostei—which translates to "cartilage bone"—refers specifically to the composition of their internal skeleton, which is primarily made of cartilage rather than fully ossified bone.1

While it is true that sturgeons possess thick bony plates on their heads and rows of enlarged scales known as scutes along their bodies, these external features do not change the fundamental classification based on their internal skeletal structure. The group represents a primitive lineage of bony fishes that have lost much of their ossification over time, distinguishing them from other groups like teleosts. Therefore, the name highlights the cartilaginous nature of their internal framework, which remains their defining anatomical characteristic.123