Zoology 9th Edition by Stephen Miller

تمرين 1

Fossils of ancient sarcopterygian fish and early amphibians, such as Ichthyostega , provide ample evidence of the evolutionary transition between fish and amphibians. Ancient stegocephalians gave rise to numerous lineages, including the Lissamphibia (modern amphibians) and the amniotes. The relationship among these lineages is controversial.
Why is the use of the "class" designation for members of the Amphibia phylogenetically incorrect?