The proto-ramjet replaced its ancestor the gasprinter. It adapted an even more effective "butt-jet". It has developed a methane sack in which to store up methane. It can also redirect its burps/farts into this sack. It will typically suck in methane from volcanic areas but can also produce methane trough digestion. It has developed a secondary butt-nostrils to breathe from similar to the original configuration.
The success of its methane storage organ has allowed it to dominate the cave ecosystem has cause the Wingless Sprinter to become extinct. Its beak is shorter and more powerful so it can crush bone with it. It scavenges as much as it can hunt. When it hunts it can use its "sneezegliding" to boost its flight and attacks. Its red crest now split into 2 crests. Its larger eyes can see farther and even in the dark of the caves. Its claws have sharper talons so it can grab onto prey on the fly.
It builds nests at side of cave walls. Females will sit there until their babies are born via live birth. The male will bring back food for the female. Once the babies are born the male will sit and protect the babies and the female will get food for them. Once grown they will all join the flock once again. While they stay in a flock to avoid bigger predators. They will however fight over dead food when scavenging.