Respuesta :
Hello!
1) Echinoderms
2. A.) Jawless fish have cartilaginous endoskeleton while Bony fish have a bony endoskeleton.
2. B.) Jawless fishes gills are exposed to the outside while the bony fish gills covered by operculum
I hope it helps!
1 - Echinoderms. Echinoderms started appearing in the Cambrian period, which clearly indicates that they had ancestors related to the earliest chordates.
2 - Jawless fish differed greatly in anatomy from bony fish, since their lifestyle was different. Jawless fish also appeard way earlier than bony and cartilaginous fish.
Hope it helped,
BioTeacher101