a) jawless fishes.
A: jawless fish
no..primitive is archaebacteria
It is as primitive as a cave man.
The most ancient group of vertebrates is generally considered to be jawless fish, particularly those in the class Agnatha, which includes lampreys and hagfish. These creatures first appeared over 500 million years ago and are characterized by their lack of jaws and paired fins. Their evolutionary significance lies in their primitive features, which provide insight into the early development of vertebrates.
Bony Fishes
Reptiles
Mammals are most familiar vertebrates .
Jawless fish belong to the group known as Agnatha. This group includes species such as lampreys and hagfish, which are characterized by the absence of jaws and paired fins. Agnatha is considered one of the most primitive classes of vertebrates, and these fish have a unique, elongated body structure and a cartilaginous skeleton.
bony fishes
bony fishes
The rainbow XD lol
The group of vertebrates most closely related to birds are probably the dinosaurs.