Ancient mob for the end

After the sniffer was added to Minecraft I began to wonder what mobs could have lived in the end and nether in the past, so I propose the addition of the ancient dragon: a small black dragon with a gray belly and gray wings, its eyes would glow green, and it would be a passive mob until provoked, then it would attack the mob/player that attacked it by flying extremely high and then diving down towards the mob/player to gain speed, it would also be tamable using popped chorus fruit or regular chorus fruit, but normal chorus fruit will have a slightly lower chance of taming it successfully. Once tamed it will be ridable if a saddle is equipped to it, it will be slightly faster than a horse, it will also be breed-able after being tamed, upon breeding one of the parents will lay an ancient egg on the nearest unoccupied endstone block. It will hatch from an ancient dragon egg that is obtained after the player locates new ruins of some kind in the end and uses a brush on the suspicious endstone located there, possibly giving the player an ancient dragon egg, but also possibly giving the player armor trim or pottery sherds (dragon armor trim, enderman pottery sherd, etc.)

This new mob could make the end much more interesting and would expand on the idea of ancient creatures that was introduced by the sniffer