Y'all don't actually need to trap it and prepare a baby Dino if U have a rhyniognatha, y'all just need to find a nearby rex or spino, carry it ALIVE to somewhere near the carcha but not near enough for it to notice U, kill the rex or spino U carried here and drag the body with ur rhyniognatha, it will be slow asf but trust the process. Once the carcha do a SNIFF animation just wait there for it to eat ur offering(btw if Ur wearing ghillie take it off just incase) and if it shows a green sign at top of it's head then congrats now just ride it and kill anything U see until it fully trust U(note that U might want a second flier or a parachute cuz rhynio won't follow U, maybe even a sleeping bag just incase ur didn't have time to react when it throws U off after tame)